I work in emissions testing. We have always found on drive cycles that the lower the revs the better for fuel consumption. The only exception is if you get so low that the go below the idle speed where the engine will open the throttle and add more fuel to prevent stall. Modern cars all have drive by wire throttles so they do this automatically.
I have noticed modern engines open the throttle automatically when the revs are too slow. Interesting to hear from somone who works in the industry, thank you for your comment.
@@ConquerDriving No problem. Love the videos. I have done some fuel testing on my own car to see what speed is most efficient. Turns out to be 35mph in 6th gear. Pretty boring in a S2000. I imagine your car's optimum cruise speed would be a bit quicker it's more aerodynamic than mine.
@D R I think your assumption is a bit out of date, as most ICE cars these day have turbo chargers which give a lot more power & torque at low RPM. My car develops peak torque from 1500 RPM.
Makes sense too. I'd wanna see the difference between 5th and 6th gear on like a 100 mile stretch of highway. The drag at those speeds matter a lot for fuel economy so it might make the difference between the gears bigger.
There was a video with an instructor exam. The learner had lessons for 5 years and she didn’t knew 1st gear exist lmao. Tried cluth control on steep Hill and drove 50 mph in 2nd. Poor car and instructor Nice video btw, I drive a Honda jazz and on manual it says 48.4 mpg on motorways, tho i m averaging 66-71 mpg
I was wincing the whole time. "Take her doon, captain. She Cannae take nae more!" Tbh it won't do any major harm occasionally. Loads are light and the engine will be designed to withstand it.
I only discovered your channel once I'd already passed my driving exam, but your advice and detailed tutorials have made me a better, safer and more efficient driver in these first post-exam months. Recently I'd gone on a 5 hour drive and it was incredibly fun and relaxing!
Hey Richard, can’t be thankful enough. I passed my test today with 8 minors. I have been driving with my international license and did not actually took any driving classes. I only referred to your videos.
@@HonkerzGang I guess you can, either you'll have to take driving lessons from instructor or anyone within your friends/family who has held a full UK license for more than 3 years. Well in my case, I was already driving for last 9 months on my International license in UK and 10+ years in India, and followed Richard's videos for technical stuff. My basic driving skills were already developed, with his videos I learnt the British driving technicalities.
I'm no car mechanic so take this with a grain of salt, but the 1st gear run probably wasn't as bad for your engine as you may think since the engine was under very little load. That's why you got decent mpg even at 5.5k rpm. If you where towing 10,000 lb at that same rpm and up a grade the engine would have to use much more fuel to sustain the engine speed and that could possibly cause enough pressure to blow a head gasket or overheat. As long as your engine had its oil up to temperature and good valve springs the high rpm theoretically shouldn't be a problem for the test you did assuming no weakened spots in the engine.
This is true, but everything (alternator, AC pump, cam belt, pulleys etc) was spinning much faster than usually for a longer period of time than usual. I'm sure it's fine but didn't feel good.
@@ConquerDriving it is made for it, thats why you have a redline lower than your car can handle, alternator and ac pump usually turn off when overloaded.
Guys don’t foget he is an instructor. He still needs His car and has more mileage on a Vag group car than more most reliable car do.. he know what he is doing.
The engine won't break but the wear is accelerated. Any prolonged high rpm will be felt down the line. No matter how much oil and coolant u use there will always be friction and heat.
Yes, the latest petrol manual cars have not improved much when it comes to efficency over the last 10 years or so. It's hybrids that have moved efficiency forwards. At least that's my experience.
@@ConquerDriving even worse, latest engines have pearticulate filters in them, which lower fuel economy. EURO-5 TSI probably are the best there'll ever be in non-hybrid gasoline engines with good fuel economy and enough power...
@@ConquerDriving Yes its kind of nuts that many smaller Hondas have been getting 40 mpg highway for 40-45 years. The only difference is that my curb weight today is more and the interior space is better. I guess we can believe what they say about thermodynamics that ICE cars are at best 30% efficient. We can probably surmise that in the US economy is not as paramount as it is in other countries because they either have smaller cars or diesel with it's intrinsic better energy/higher torque.
@@jamesmedina2062 A 40 year Honda that gets 40mph highway is a 70hp tinbox with bicycle tyres, there are 2 ton 300+hp petrol cars today that can get 40mph highway, while blasting the automatic air con and massaging your back. Don't compare things that are incomparable.
@@BigUriel Not possible man. The way engines are designed, the powerful 2.0L turbocharged engines capable of pushing around 4000 lbs have no way of achieving 40 mpg mixed driving which is what matters. The GTI has nice gearing and can achieve close to 40 mpg on the highway only. But it is not 4000 lbs. The curb weight is like 3200 or 3300. And besides the heavy weight most vehicles are double the height of traditional cars so they have far inferior aerodynamics. So for all the fantastic computer processing, timing adjustments on the fly, and thermodynamic advances fuel economy is not that good. Look at the vast majority of vehicles today and be honest please. The trucks get less than 20 mpg and the bigger cars and SUV get mid to high 20's. Slow highway driving on flat ground doesn't count. I can get 55 mpg on flat ground at 55 mph. My typical 75 mph in town highway and the hills here cause me to get 37 mpg and thats with 1.5T and 2780 lbs curb weight in car with the benchmark for engine efficiency.
yea this video largely ignores that aspect of this but it is important to note that using a higher gear like this for better economy is only applicable when cruising on near level ground because in such cases the cars speed can be almost entirely maintained by momentum and the engine isonly required to provide slightly more power than what is needed to keep the internals spinning
No. The injectors will not spray more fuel into the engine due to the Lambda and the amount of air coming in. It's just like biking: you have to select a lower gear not because you use more power but because you are not able to deliver the torque. Power = torque x rotational speed. Power does not change, so you have to increase rotational speed to lower the torque.
The energy requirement is the same. You have to raise the potential energy of your vehicle when climbing. If you cannot generate the amount of power required, shift down. That's what the gearbox is for.
I loved the nuanced summary that you gave at the end. It's important to note that it's not just the engine that gets damaged by under-reving; It's also everything else between the engine and the wheels.
When it comes to gear choice and fuel efficiency, you're trying to balance 2 things: pumping losses and thermal efficiency. The faster the engine spins, the harder it has to work (the more power is required to overcome the act of) sucking fresh air in and pushing exhaust out of the combustion chamber. This means the lower the rpm, the less pumping losses there are, and the higher the rpm, the more pumping losses. More losses is bad for fuel efficiency, so lower rpm is good for fuel efficiency. Does that mean the lower the better? Not so fast. There is also thermal efficiency of the engine. The engine has an easier time extracting kinetic energy from the burning fuel at some rpm rather than others. At very low rpm, the pistons are moving too slowly to absorb the energy released by the burning fuel, and at very high rpm, the pistons are moving faster than they can accept the energy, so a medium rpm has the best results for fuel economy. There is also throttling losses in a gasoline/petrol engine, and when the throttle is mostly or partially closed, there is some restriction that the engine must overcome to pull in air, so very low throttle inputs are also not great for efficiency. When you combine all of that, the most efficient rpm to use depends on your engine's thermal efficiency curve and how much power you need at the given moment. If you need a small amount of power, typically you want the lowest rpm the engine runs smoothly, typically 1100-1300 rpm or whatever your highest gear allows. If you need to make a lot of power to accelerate or climb a hill, you want to go into the thermal efficiency band a little more which varies by engine, but most reasonably sized engines are going to be most efficient between 2000-2500 rpm. Going faster than 3000 rpm on a normal engine is wasting fuel no matter what, but sometimes you just need or want the extra power. You also want the throttle opening to mostly open if possible. You don't want it open fully (accelerator to the floor) because then the car's computer might start asking the fuel injectors to make the engine run rich which isn't great for efficiency either.
I passed my test back in december 2018, but i’m gonna sub purely because the stuff you post is interesting :) I’ll probably end up learning something new
Thank you so much Richard for all your wonderful videos, your videos are the main reason I cleared my exam on the first try. There were things that my instructor failed to tell me but through your videos and your plain explanation, it was made very clear what I was doing wrong and how I could correct it. On YT I have only seen your videos that tell what happens if you do something wrong instead of only telling how to do something like 99% of other driving videos. Cheers.
It's actually good for your car to do some high RPM runs now and again, it's a good way to clean out the exhaust and cylinders. Lugging your engine puts strain on all the parts and kills it quicker, accelerating from 20mph to 70mph in 5th gear all the time will kill it pretty quickly.
Yes. I love letting my Honda with 6.2k redline sit at 8k rpms for hours at a time. Runs like it never has before. -sarcasm Seriously though. Nothing wrong with doing some quick accelerations, if you're not pushing to rev-limiter every day :D. The autos love to rev out a bit.
Complete bullshit, running with low revs (but still above idle) does not put it under strain, the piston speed is at its lowest and torque is also low. There's nothing wrong with revving the engine, but carbon build up will happen either way, becaus even if you don't think about it, you have tubput the engine under load now and them, to climb a hill or pass someone on the highway. Use some fuel additives to minimize it a little.
Great observational experiment. I never properly drove a true manual but can appreciate the thought a driver must make in regards to gearing, flexibility and safety. In my old diesel DSG car it was fantastic how low I could get my revs with the car handling it fine. I always watched the KpL info when doing diferent gears on different grades in manual mode gears. The observations from this video match my own. Diesel is a fantastic choice for economy. MY current turbo petrol has a dual clutch also, quite a bit of pep, but gosh I miss diesel economy and torque creeping.
Really needs to be repeated at a higher speed (at a test track, old airfield or something). Above a certain speed your car's mostly fighting air resistance, meaning higher torque required to maintain speed. Curious to know if results are different at 60MPH
No. Lambda is is master over the engine - in closed loop- and fuel injection. So: the lower the revs, the less air goes into the cilinders, the lower the fuel intake.
i'd also like to know how speed relates to efficiency. i get better mileage at 45 mph than 30 mph but above 60 it appears to start going down again. i'd also be interested in the difference between gearing on the same car, for instance my automatic vette has much longer gears than a manual one so i wonder how much better mileage i get
The results wouldn't be different at 60 MPH. The only way they can be differrent - if the car goes steep uphill at 60 MPH. Then 5th gear may be slighthly more economical. The cruise control on VW MQB cars (such as this SEAT) is set for best economy, with 7 speed DSG it would shift a gear lower when going uphill at high speed, from 7th to 6th, even though the engine is capable to pull the car uphill at 7th gear. If there's no special eco mode in DSG (just drive and sport) it would keep one gear lower without cruise control, to give the driver a bit of acceleration without downshifting, if needed.
Thank you so much for burning your fuel and letting us know how to be economical. I love your subtle comedy. I always try to be in "right gear", the higher the better. I've a hatchback with 1000cc three cylinders engine, kinda family car, nothing sporty. Few days back, I called a driver and let him drive. He used to change gears really very late. Like he goes, 25mph with first, 35mph with second. I hated it and took over the controls. It was eating me up from inside, not just because it was consuming whole lot of fuel but also because I couldn't bear what my engine was going through. I know, that is fine if you're in a race, wanna speed up as quickly as possible. Performance over economy!
This videos, on your channel are great! I have my license from 2016, but the learning never stopped. Actually, there was much more learning going on, regarding driving, from your lessons then from my driving instructor or any other driver or circumstance. Thank your for your effort and dedication!
i have done the same tests with my 2022 suzuki swift with the k12N engine. I have seen that when going uphill, sometimes using higher gears causes more fuel consumption. and 99% of the time the gear the car wants to use is the most efficient.
The optimal drivetrain for low speeds is the Toyota HSD, just having the engine run for a few seconds at its most efficient point and then using the electricity fed to the batteries to move forward
You should also mention that this is for petrol mostly. In practice, higher gears in a diesel CAN and DO consume more fuel if you're not in the correct gear. It's because in a diesel the car suffers way more when out of ideal gear than petrol. From my observations, let's say we're going 50 km/h, optimal gear in a 6 gear manual is probably 4th. 4th and 5th are going to roughly give you 3.2L/100 km if cruising. But shift to 6th gear, if the car doesn't like it I have seen it go to 3.5 in practice, and 4 or even 5L/100km for any tiny bit of acceleration. I could keep in 4th and it's also going to go to 5L/100km for acceleration, but this is going to happen over a shorter period of time. I could go to 3rd gear and then it will go to 7L/100km for an even shorter period of time. Going to 3rd will be better if you're going slightly uphill, staying in 4th will be better on a flat surface, especially with the turbo most diesels have. Obviously, when above the ideal gear it's not going to scale like 1st and 2nd gear, where the computer may show anywhere from 30-99L/100 km, but you should not torture the car if you have a diesel since they're more sensitive about revs.
Depend on the gear ratio too,Skoda yeti diesel (manual 6 gears) of my uncle 50km/h in 5th is ok. With my manual 5 speed audi A4 (2003) 1.9tdi,i can cruise at 50km/h in 5th gear, the engine still happy,take time to pick up speed but,fuel efficiency is there. Form various cars i have drove,70km/h a good mix between fuel saving and resonable speed,90km/h ideal speed on highway for not be too slow and manage fuel saving (trailling truck helping too).At 100km/h fuel saving start to be bad unless following a truck,above 110km/h fuel saving is none
@@waynelau3256 You could probably do it in a 10-12 speed automatic with paddle shifters. If the ideal speed is 4th lets say, you put it to 7th or 8th. Of course, you're not going to have much torque, sure, but you'll likely need more gas than in lower gear to cruise at the same speed. The thing that is important is to exit the most efficient RPM range. You could probably see it if you try to start from 3rd gear (although unsure if you'll have enough torque, a diesel can start from 4th even so it's easier to see). You would think that it's all the same, you try to spin the wheels, your additional spin is converted into torque and you take off, just at higher revs... But at higher revs your engine is less efficient, so there is less work you can do, and that means that for the same work you expend more energy. In diesels you lose efficiency after roughly 2.5-3k revs and it's easy to see. In petrol you might need to go above 5k depending on the engine. Some petrol engines redline at 5.5k already so it might be difficult in practice xD
I have a 1.6 mini one from 2006 and I can use 5th gear at 30 just fine and it revs to abt 1300rpm on a flat road. Using 5th when possible instead of 4th and taking my foot off the pedal and coasting towards roundabouts and downhill got me from around 44-45 to 59-60 which has saved me tonnes in money as u would expect. Always happy to see videos of actual results like this. Really useful thanks so much!
For some reason, I'm always surprised at how good the fuel economy of european cars is. Here in the US, getting over 40 miles per gallon (US) is considered really good. Most cars I've seen tend to sit in the 20-30 range.
In the 90's I drove for 10 years my 1,3 Toyota Starlet like this (5 gears only though) and there was no problem with the engine even after 163.000 km, when I sold it. Gota a soon as possible on the higher gear and "listen" to what the engine told me. Great Video!
Excellently done. The only comment I can think of is economics. If you are conserving gas for cost savings you might want to weigh that against the potential greater engine wear of using too high a gear (and thus very low revs.) At what point do gas savings get over come by the cost of an engine rebuild? Hard to calculate. The problem isn't in cruising at low revs, but when power is needed at low revs. The term I've heard for that is "lugging" the engine. This is especially hard on turbo-charged engines. That said, if power is needed, its easy enough to downshift, apply power, then shift back up for cruise.
I really like your videos, I appreciate how transparent and evidence-based your approach is. As well as your driving tips, I feel like I'm learning how impressive that 1.4TSI engine is!
Thanks for the effort! For what it's worth, I'm keen on economy when towing a caravan with a Passat Estate 2 litre TDi 150PS. Definitely better MPGs in 5th than in 6th (top) gear. I get around 38MPG at 45MPH cruising, over a full journey, without slip-streaming. However... I have adaptive cruise control ACC which is basically a radar connected to the throttle AND BRAKES. If I can tuck in behind a big lorry, at typically 55MPH for long stretches of the journey, I can get 40-43MPG over the trip. Without the caravan, 65MPG averaged over a tank (with mixed economical journeys) is achievable. Given the 66 litre fuel tank, this is more than 900 miles range.
I want to add that direct fuel injection and port fuel injection behave very differently at very low rpm. Normally direct injection has a major advantage over port fuel injection in terms of efficiency, but at very low rpm (under 1300-2000 depending on the engine) direct injection will struggle to mix the air and fuel together well enough, resulting in poor efficiency, whereas port injection has excellent fuel mixing at the 1000-2000 rpm range so this test will have a different results if done on a port injection engine.
@@thepurdychannel8866 While the cost of such systems is higher, they do have the best of both worlds. They all rely on a combination of direct and port injection at low rpm and by 1800 rpm they almost all rely strictly on direct injection.
Definitely depends on the car, my 63 plate Diesel Focus can handle 30 in 4th, but unless the road is perfectly flat and there’s no traffic it’s better off in 3rd. Ends up being more efficient if there’s any hills, and definitely more flexibility. My wife is actually learning to drive, and her instructors car is better off in 4th at 30. Good learning for her to get used to other cars gear ratios as well in this case.
Agreed, actually my car can cope in 5th gear rather well at 30mph just a needle under 1500RPM, it can even do 25mph in 5th gear although the engine does growl and ask for a lower gear at that point, the gearing's quite high on my 1.6 petrol Focus.
My dads car ( Ford C-Max 2014) cant do 4th at 30mph. When i get above 55kmh(dont know exactly mph) i shift into 4th. Its a diesel btw which explains that.
Did a similar test with diesel, Ford Smax 2.0 TDCi 140 and Peugeot 5008 1.6 e-HDi EMG. Not using all gears like you did though, but only the more appropriate once, 3,4,5 or 4,5,6. 1 stretch flat at 40 km/h CC 1 barely uphill at 50 km/h CC 1 uphill with sharp turns, 50-60 km/h non CC. So steep that going down, you can neutral-coast and maintain your speed around 60 km/h. Don't quite remember the differences, but I was surprised how high they were, and how low you could go with rpm. Basically my numbers pretty much match your numbers as far as I remember. And the highest/heaviest gear gave better consumption as long as the engine was able to make usable power. Especially in my "steep" uphill-test they struggeled in 6, especially the higher geared Smax, as in one turn you'd want to go at around 40 km/h. Tried to modulate throttle to not have them struggle too much, but took long time to build speed again and that really hurt consumption. Tried 6 with 5 in slow corners, but there wasn't much in it compared to just staying in 5. Done that one turn quick enough for 6. though, and that would be the winner.
The full use at second gear is nearly half the fuel usage at 1st, when the rpm is about half aswel, funny that. At lower rpms the engine throttle position becomes more relevant. Cool video, really enjoyed it.
Really interesting video. When I used to drive a manual, I was eager to get into a higher gear as soon as I could (not that I realised that I was saving fuel). However, and as you are probably aware, there are many variables which this video didn't really take into account. Wouldn't it be good if there was some kind of website that published figures which took into account all the variables for a range of diferent cars.
That would be intersting, but generally, if the revs are low you use less fuel, if the revs are so low the engine struggles then you don't save fuel. I think other variables would make a small difference, for example - low revs vs higher revs at cold temperatures.
A minor point on older diesels (2000-2010 ish), most of them tend to run quite lean, especially throttleless designs (like PSA's older 2.0 HDi engines), so they tend to be quite good under light load even at higher revs. They also have a fairly narrow band of efficiency (the HDi sits around 2k rpm, ±250). Running slower results in dirty combustion under power, clogging up basically everything, and running faster ups parasitic losses significantly, though the odd Italian tune-up is still justified. With most diesels, it's still best to accelerate under nearly full power. This is because they reach their peak thermal efficiency under full turbo pressure (this is where older unthrottled designs tend to edge out - full pressure grants peak efficiency, but that's not necessarily all the power available). The same holds true for petrol engines too, but the efficiency gain there is smaller and, whereas in a diesel, this outweighs parasitic losses from within the engine, in a petrol engine it doesn't. And in new diesels it's all different too, NOx emissions regulations preclude lean combustion to the extent possible with the older models, so they behave more like petrol engines.
Right, i remember getting a new company car in 2014, Fiesta 1.5cdti, and being amazed how easily revs to 5k and the torque feeing so linear from 1.5k to 4.5k rpm. Funny thing, modern petrols like 1.33 dual vti from Toyota pulls at low rpm like a diesel!
@@FSXgta The 1.9TDI is a pretty neat example actually. From an owner's perspective, as long as you don't run it on supermarket fuel, it will probably outlast you (the DSG... not so much). But more importantly, it took 30 seconds to find a brake-specific fuel consumption (BSFC) map for it. (x-engineer.org/wp-content/uploads/2017/08/Brake-Specific-Fuel-Consumption-BSFC.jpg) On the X axis is engine speed (rpm) and on the Y axis is cylinder mean effective pressure. Inginerd speak for torque. The contours represent BSFC and for fuel efficiency we want to keep that one as low as possible for the required power. The dotted red line on top is your dyno torque curve. Note the flat bit in the middle. That's a limit imposed by the boost controller (for many good reasons), but it's also the ideal acceleration range in this case, per the bsfc map. Ideally when accelerating you want to sit at about 80-85% of max. torque and around 2200 rpm, and presumably VW were intelligent enough to programme that into the DSG's software. Once you're up to speed and off the throttle, your torque demand goes down, thus the rpm ought to go down too, otherwise fuel is being wasted. What you say about adding more throttle makes perfect sense. In higher gear you need more torque to make the same power, plus at higher speed you need more power to maintain acceleration anyway, so naturally when the DSG upshifts the car will need more throttle. If you look at this map though, you can see what it's doing. By forcing higher torque at lower rpm under moderate acceleration it's pushing you up into the engine's efficient region, where it makes the same power with less fuel. If I'd been the one deciding the logic though, I would have made gear changes as seamless as possible. Given that these engines essentially run under FADEC (look it up), there's nothing stopping the thing automatically increasing engine output to maintain either constant power or constant acceleration (assuming *moderate* acceleration). With all the pointless "customisation" options they offer, you'd think someone would have thought to let you set preferences for important stuff like throttle logic and responce.
Thanks for the awesome Test! (Not a mechanic here but:) I believe the 1st gear run wasn't that bad for the car, considering the high rpm you get, when driving high speed. I regulary drove an old renault megane 1.6 16v on the Autobahn with about 190-210 km/h (~125mph) (should be around 5500 rpm) at which it would get much more stress on the components, i guess, however, this thing runs perfectly fine since 2006ish. No problems at all. Frankly, most of the time, i weren't exceeding 160km/h (100mph) because i gets quite noisy then, but sometimes, when theres lots of space and little time, i went full throttle for about 5-10min at a time. The fuel consumption rises exponentially at that speed, therefore i don't often drive like that, nowadays.
Very glad to see a video showcase this bit of (what seems to me like) common sense. As long as you're not lugging the engine, lower RPM always = less fuel. I too stick to 5th at 30 in our 2011 Astra. Most of the time I just get to speed in 2nd and then just jump to 5th, as I'll only be in 3rd or 4th for a few seconds if I bother. Obviously that's if the road is clear ahead to be able to reach 30 quickly.
In my BMW E46 I swapped the diff for one that is slightly longer. Dropping the RPM by roughly 400 rpm at high way speed (from 3000 to 2600). The gain in fuel economy is noticable for sure.
My main tip for fuel savings (I realise this is a little off-topic) is don't accelerate to the place you're going to start braking. So many people accellerate to off ramps and then stamp on the brakes to scrub off the speed they've just paid for. Likewise the constannt accelerate/brake style of urban driving so popular with teenagers.... yes we all did it, but its a good habit to break. So ends the second sermon.
@@boobo You probably misread it; it doesn't say accelerate slowly... it says don't accelerate pointlessly. IE: "Don't press gas AND brake" which is in fact great advice.
I like your thorough methodology and presentation with US units included. You have a new subscriber for sure. I drive a 2012 Toyota IQ with the 1.3l petrol engine mated to a CVT, have done for 10 years and 200k miles, so the idea of individual gears doesn't apply to my car, but the behavior of the computers that control both the CVT and the throttle seems like they want to do exactly what you're suggesting here. There doesn't seem to be any problem with the engine pulling me along at around 1krpm at neighborhood speeds and around 2k to 2.5k at US highway speeds when being easy on the throttle in eco mode. It idles at 500 when I come to a stop, which felt a little rumbly and worrisome when I first got the car, but 10 years in it's just normal. But basically the computer is setting up my CVT to be in a similar ratio to where you're at in the 5th or 6th gear test depending on the grade of the hill, and I'm assuming Toyota's engineers spent a lot of time working out the precise efficiency curves so they can plug in just the right numbers into the computer to maximize that MPG number for marketing purposes, so the fact that it all lines up based on your data here is just proof in the pudding. I'm assuming probably any other small 4 cylinder made in the last 10 or 15 years can probably do the same.
I did a similar test to this, only with highway driving and managed to find that between 4th and 5th at 70mph (3,000 RPM vs 2,500 RPM or thereabouts because my car has an analg tach) and I managed to get 34mpg in 4th and 51mpg in 5th.
Don't know why but when I'm driving in steep hills, I always try to find the upper most comfortable gear for the engine (if I press the throttle harder and the speed doesn't increase, then I assume that I am in the wrong gear and downshift) and try to keep it in the RPM where the engine develops peak torque. In my mind, by keeping in peak torque RPM, the engine will produce the maximum force so I won't use as much fuel as it would in other (perhaps upper) gear when going uphill. Nice video !!
Dropping in to say thank you for these videos! I passed my driving test with only one minor (or something like that, the Finnish system is quite different) today. Your videos were really helpful even though I did have to adjust slightly since we drive on the other side of the road, and Finnish roads are less of a wild west compared to the UK somehow.
I've just moved to a six speed gearbox, and it's always telling me to change to 4th when I hit 30mph. I feel I've had to completely relearn my understanding of acceptable revs ect. Interesting to know you were taught to sit on 3rd when learning, I think I was too!
key is that a hill or acceleration will require a quick downshift to 3rd but for steady pace, 4th is just barely sufficient unless also you are at sea level and very flat area.
I tend to leave it in 3rd at 30mph because I'm fastidious about keeping to the speed limit and I find that 4th gear creeps up more easily if you're heavy-footed. I might try using 4th and laying off the accelerator a bit based on this. That being said, mos of the time I ride a motorbike that gets 150+ mpg so not much of a worry.
Thanks for your videos you've made me better driver than my driving school. And it is also nice to watch you, you have some kind of Jim Carrey vibe tbh
Richard fantastic video as always. Can you do the same with the diesel engine? I am curious because the diesel engine does not have the throttle valve, in theory keeping the rpm very low is not good for diesel engines because of the egr system and the fap filter I think.
At low rpms, you’d likely be loading the engine which would hurt fuel economy because the engine needs to inject more fuel to maintain speed. Under such load, the EGR should also be less or completely inactive. EGR might reduce the lifespan of diesel engines, but they should have little effect on fuel consumption.
Great video. My advice keep your revs under 2000 rpm. In all gears. Also get to top gear as fast as possible. If you can look ahead, consider coasting up to traffic lights. Anything to lower revs. Basically the heavier your foot, the more you spend on fuel.
Fuel economy is usually directly correlated to how much you put your foot down. Even if you are on 1000rpm, upon flooring it, the car gets the message that you want to accelerate and will pump lots of fuel to compensate for lack of horsepower at low revs. However, most cars especially in steep hills or under heavy load will struggle with 1000rpm. So it's best to build momentum before climbing hills and ensuring the car is at the rpm where it's most efficient during the climb.
you are right on efficiency but wrong on "will pump lots of fuel to compensate". Power is not increased directly by adding more fuel, it's increased by first opening throttle to let more air in, and it only add more fuel when the air flow has increased.
@@francoisloriot2674 Many modern cars have the option to display live consumption that refreshes every second or so. I noticed that if the car is on low rpm and struggles to climb a hill, it will pour more fuel. For example if I am at 2100rpm on a turbo diesel engine, I only need to press the gas pedal slightly and get decent power with good efficiency (eg 3.5lt/100km), but if I am on 1100rpm that value always increases to something like 12.5lt/100km even with little throttle input. If I fully depress the gas pedal while on low rpm it can go over 20lt/100km, especially on lower gears plus the engine can be damaged by driving with too few rpm. Bet it's some sort of system that shoots more fuel to prevent stalling.
@@orm6922 again, it will not add more fuel (unless the conditions call for a richer mixture). if you want the details: to prevent stalling it will open the throttle blade a bit more, the Mass Air Flow sensor will detect an increase of air, ECU will then increase the duty cycle of the injectors to keep the air/fuel ratio. What some people call a 'gas pedal' (true name is accelerator pedal) just cause more air to get in. The ECU does the rest. Yes, in the end you will have more fuel, but all I wanted to say it's start by adding air and not fuel.
My highest gear, 5th gear, drives at about 3k revs at 60mph, and 4k revs at 70mph, It's a very close ratio gearbox. It doesn't tell me my fuel economy but it does feel awfully consuming. Good video
What displacement? The manufacturers' engineers seem determined to keep the drivers out of lugging potential because that can cause issues. Higher revs in some 4-cylinder engines utilizes momentum to control the car at its highest gear, with say 130-150 HP whereas a GTI with 230HP in MK4 would turn at 2000 or even 1900 RPM going 60 mph since it has higher displacement and power.
Low revs are great in a petrol but man, in a modern diesel they can cause all sorts of problems with the assortment of filters they have, specifically the DPF and EGR are common faults. A friend has an automatic mazda 2.2 skyactive around 5 years old, and it keeps the revs low with the tonne of torque the engine provides and even though he does mostly long (50km+) journeys on the motorway, he's currently got massive problems with the dpf and cat. Another thing is the Dual Mass Flywheels that tend to self destruct when people get remaps for fuel economy (which in a diesel just means more torque lower in the rpm band), massively more load on the DMF (an expensive part to replace) ends up burning all the potential fuel savings. A personal experience, my dad has a remapped 1.9jtd which can pull with ease from 1800rpm in 6th, but it also destroyed the weak bearing in the infamous M32 gearbox which cost over 600eur to repair.
Amazing test! Would be interesting to see the same test but going slightly uphill, to see how much increased resistance affects fuel economy in different gears. I'm pretty sure that at some angle 4th would be the best choice.
I'm sure that would be there case, I don't know of a quiet hill that's long enough to register an economy reading and quiet enough to make the test possible.
Thanks for doing this test. It pretty much lines up with my intuition diving a manual. I always keep mine in the highest gear comfortable. I once rode with a guy who always kept his near 3k rpm. I'd hate to be paying his fuel bills! I would have liked to see a test in both directions for every gear, to average out slope and wind.
It really does depend on the engine and transmission. In general, spinning the engine slower reduces parasitic losses, HOWEVER there are plenty of other things that come into play. For instance, when revving higher you pump a whole lot more oil throughout the engine, so as long as you don't sit in some resonance mode (for inline 3s and 4s, for instance) it's fine to rev. Thermal efficiency will also vary, with load as well as revs. Manufacturers use brake-specific fuel consumption maps to determine optimum speed/load maps for automatic transmissions. This lets them sit in the highest possible gear when under very light load (as there's no power needed) and as soon as more power is commanded, those transmissions drop right down into a suitable gear where the commanded power is delivered most efficiently (unless you're in sport mode of course 😉). Humans don't tend to think in such terms most of the time, so recommendations tend to focus on being the safest option for "most situations" (i.e. including uphill etc). But yeh, it really is down to each individual vehicle. My 650cc bike for instance quite happily cruises in 4th at 30mph, and can do so in 5th and 6th, but if I'm in 4th I get steady operation (some performance engines run rougher at low revs), excellent fuel economy and enough torque for "normal" steady acceleration if needed. By virtue of it being a fairly high-revving engine (red line is upwards of 12k... and that howl! 😁), I don't imagine cruising in 5th or 6th at 30mph would be particularly healthy for it. 40 is fine for 6th though. The other thing to take into account is air drag. At 30mph there's none. Not as far as the car's concerned anyway. Most parasitic losses come from within the engine at that speed, so your test results make perfect sense. It starts to become a factor around 50mph and becomes the dominant phenomenon upwards of 60. So if you repeated that test on the motorway, I would expect to see much smaller differences between 4th, 5th and 6th, though 6th should still win, even up a significant incline.
I have been driving these way long back when i become expert. My instructor told me, no matter what dont let the engine jerked on higher gear, but always try to drive with low revs higher gear. And yea 106000 miles completed still my engine is rock and solid.
Two big reasons against eco-driving and avoid low rev/higher gear: 1) low revs cause stronger vibrations which translate to quicker wear and tear of car parts especially two mass flywheel installed in most diesel but also petrol cars 2) diesel only - dpf (particulate filter) to self-clean it needs higher burning temperatures and revs 1500-2000 for prolonged period of time, otherwise it will clog (which means stop for a car) and is quite costly to replace
Actually, more throttle opening means less pumping losses on a gasoline engine so you can only benefit from opening throttle. The reason you have better fuel consumption with lower revs is the fact that you have less losses in engine friction. However, every engine has a sweet spot in terms of revs and load where brake specific fuel consumption (BSFC) is minimised by design. By going in higher gears you're effectively going up in load and reducing BSFC. What you're testing is exactly that, same torque request but at lower revs and higher load 😃
Understood, now I’ll only drive at wide open throttle!
2 года назад
Dude I'm kinda jealous of how well your car is maintained. I own a 2012 Citroën C4 GLX 1.6 (Petrol) with only 125.000 km on it and it is way more negligenced than your Leon. I don't have a covered garage though, and I have to keep it parked under the sun all year round. Thanks for the video and the explanation. I love these VW TSI engines.
I would be interested to see what the best fuel economy you can achieve driving at 20mph, 30mph and 40mph. Politicians are forcing 20mph on us in many areas under the claim of reducing CO2. I think CO2 emission will be higher at 20mph for the same measured distance as the fuel economy will not be as good as a car travelling at 40mph in 4th (1:1 gearing) or higher over the same distance.
youre right. 20mph is polluting the air via the tailpipe more than 30mph. BUT those low limits are mostly in the city where you will do a lot of braking (brake dust). Also because of the low speeds the tyres wont be worn so much (rubber dust) and same with the street (asphalt dust). All in all in does not improve nor harms the pollution. The most important benefit is safety and noise.
@@razor_ramon_ well, all cars with automatic transmissions with a manual mode are still automatic. Just some of them also have a duel clutch (more efficient)as opposed to a torque converter(less efficient).
@Geo’s radio & musical stuff yeah, they have gotten a lot better over time, but still they work off of fluid dynamics. In theory, the faster the torque converters driving impeller is, the more efficient it is to a certain speed. At the same time, the faster an engine spins, the less efficient it gets. So I would love to see where the perfect balance is between engine speed & torque converter speed where they overlap best for the best efficiency.
@@razor_ramon_ mine lets you stay in whatever gear you choose, but yeah you're right, a lot of them that have "manual" mode just let you set the max gear that it will automatically shift to
Not many manual shift cars in the USA because people don't want them anymore. But both of my cars are manuals. I happen to prefer them. In those newer CVTs you have no way to control what RPM you're at at whatever speed you're going. The older traditional automatic transmissions you could manually select your gears but they might have only had three or four gears.
General rule: Drive in highest gear possible with the least amount of accelerator pressure possible (usually, that's around 2-3k revs). That is also a good advice for driving when the road is snowy or icy...
That's just wrong .. better accelerate fast with lower gear to the desired speed than slowly shift gears in order to save fuel. Its situational yes but in most cases just get to the desired speed then switch, ideal is at the 4-5k revs rather than the 2-3k, the reason automatic gears don't do it is because they don't want weak minded people to panic when they hear high revs and also want the car to be quiet, otherwise it would hurt the marketing of the car to the common plebs.
@@EliranC Exactly! You switch the gear down to accelerate and then switch it up when you resume cruise. Most cars that I drove that have an automatic gearbox do the same.
I was taught to get to my highest available gear as quickly as possible, so long as it was a normal gear rather than an 'overdrive' and so long as engine was not struggling. I was taught in 1970, using a 4 speed 1600cc and a 3 speed 3 litre. This has worked reasonably well for me since, as you say listen to the engine. Diesels can use much lower rev count, mine was red-lined at 6000 but I rarely went above 2500.
Always open the throttle as much as possible when accelerating. Use a lower gear if you need to accelerate quickly, use a higher gear when you can accelerate slowly.
it's really important to remember that fuel economy is not all that matters. higher revs with less overall load per revolution may cause less wear and tear on the engine itself, reducing maintenance costs.
When you make the motor work harder at low rpms to run, you are opening ghe throttle all the way, reducing pumping loss. Making it mote efficient. Some cars have computers that will open the throttle and mess with fueling to minimize pumping losses without revving up
No matter what, as long as your car isn't "coughing", higher gear always yields better fuel economy. However, do keep in mind that the engine is gonna wear faster because it's gonna need much more torque, which translates into strong mechanical forces in the engine components and drivetrain. It's not so much of a problem for strong engines (diesels and large displacements) which were designed with keeping such torques in mind, but most small displacement such as 1L 3cyl. gasoline engines will wear a ton faster than you'd want them to.
great video, thanks! The only thing I just want to add to that is the turbo diesel cars change their behavior greatly under 1500rpm range. Driver would need more precise downshifts even in the slightest uphills.
Fantastic video! I'm here in the USA and have a Mazda2 ( 1.5 direct injection, no turbo ) with a 6 speed manual. Been hypermiling since 2007 and have noticed in all cars that lower RPM is always better. This car loves 6th gear at 40mph / 63km/hr and i typically go full throttle from 1st gear to 4500rpm to 2nd gear 4500rpm and jump up to 6th gear and cruise at around 1100 RPM indefinitely. Most hypermiling advice would tell you to accelerate slowly but i've found that more time at low load means slightly worse fuel economy.. so basically i hammer it from a stoplight and get into 6th gear as fast as possible... but don't redline it :) The car has no engine braking so i tend to throw it into neutral coasting or needing to decelerate to a stop light... the car has skinny tires and is very aerodynamic so it can coast a very long distance. End result of driving the car this way is 45.6mpg USA MPG / 54.76 British MPG.. the car was rated 35 USA MPG average and i do 50% city driving. It's impressive. On long highway stretches if i maintain 60mph then i am seeing 60-70MPG US in 6th... quite amazing!
I always liken it to riding a bike and consider your legs to be the pistons, there's always a right gear to be in for whatever forces are acting on you to slow you down whether it be ground friction, air friction, or gravity. The one main difference is that engines have flywheels of varying weights depending on engine size/type, a car with a very heavy flywheel will be much happier up an incline in a higher gear at low revs, or maintaining motorway speed in a headwind without needing much more throttle. It's a bit of a case of know your car. The tests done in 1st (and maybe 2nd) gear might be slightly inaccurate comparisons due to newer turbocharged cars having a different boost curve for those gears to put less stress on the transmission, particularly the case in diesels, and as the turbo is a fuel saving device it's not used to its full potential. All the same, a great video where there are so many variables. If your Seat was a diesel all you'd need to do is convince it that it's being tested for emissions and it would achieve +20% mpg and emit fresh air and rose petals out the exhaust ;)
I have a 1.9 Diesel, my son has a 1.4 diesel; same model car, same age and similar milage. At 30mph in fourth gear his engine is very comfortable whereas mine, with more overall power BUT taller gearing, sounds laboured. Despite that, in my car 4th is still more economical than 3rd at that speed. It’s all about the ratios in the gearbox and the characteristics of the engine - which with some turbo cars can be difficult to predict.
I don't think so, my Mazda has no turbo and loves high gears as well. Modern engines have so many features now to help them run well at different rpms.
I would say, the exact amount of gas you are saving does vary car to car. For example, if you also had the same car from the video with the same specs, your fuel economy will vary slightly. This is because wear and tear. Also, for my fellow automatic drivers, the car is designed to shift up into a more fuel efficient gear when you aren't accelerating and it shifts down when it's to accelerate when you give it throttle. That means you can manipulate an automatic a little bit to shift when you want, for high to low pit the pedal to the metal, for low to high ease off the throttle.
Believe it or not, if you run your car at high revs but low load for a short run like this every month or so, it can help to clear some of the emissions control systems and carbon build up in certain components. More-so if you run some Redex or V-Power petrol through it. Useful to do before an MOT where they do an emissions check.
If you have any fuel consumption meter, you can read that in higher gears the consumption is lower. However other problems can occur. As the Power is Torque times rev, lower rews mean higher torque. As torque is proportional to the forces in the piston, it causes high friction and wear in the engine. Since i have a pluginhibrid, where i can not influence the revs, is see, that it runs on a safe side, especially when cold, at medium rews with low torque.
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I work in emissions testing. We have always found on drive cycles that the lower the revs the better for fuel consumption. The only exception is if you get so low that the go below the idle speed where the engine will open the throttle and add more fuel to prevent stall. Modern cars all have drive by wire throttles so they do this automatically.
I have noticed modern engines open the throttle automatically when the revs are too slow. Interesting to hear from somone who works in the industry, thank you for your comment.
@@ConquerDriving No problem. Love the videos. I have done some fuel testing on my own car to see what speed is most efficient. Turns out to be 35mph in 6th gear. Pretty boring in a S2000. I imagine your car's optimum cruise speed would be a bit quicker it's more aerodynamic than mine.
@D R I think your assumption is a bit out of date, as most ICE cars these day have turbo chargers which give a lot more power & torque at low RPM. My car develops peak torque from 1500 RPM.
@D R Turbochargers are now very common on all sorts of different cars. It's not my fault you're about 20 years behind the times.
Makes sense too. I'd wanna see the difference between 5th and 6th gear on like a 100 mile stretch of highway. The drag at those speeds matter a lot for fuel economy so it might make the difference between the gears bigger.
That first gear run... the things you do for us 😂
😂
Italian tuneup .. for the whole drivetrain :D
There was a video with an instructor exam. The learner had lessons for 5 years and she didn’t knew 1st gear exist lmao. Tried cluth control on steep Hill and drove 50 mph in 2nd. Poor car and instructor
Nice video btw, I drive a Honda jazz and on manual it says 48.4 mpg on motorways, tho i m averaging 66-71 mpg
😂
I was wincing the whole time. "Take her doon, captain. She Cannae take nae more!"
Tbh it won't do any major harm occasionally. Loads are light and the engine will be designed to withstand it.
I only discovered your channel once I'd already passed my driving exam, but your advice and detailed tutorials have made me a better, safer and more efficient driver in these first post-exam months. Recently I'd gone on a 5 hour drive and it was incredibly fun and relaxing!
That's really nice to hear, thank you for watching.
Hey Richard, can’t be thankful enough. I passed my test today with 8 minors. I have been driving with my international license and did not actually took any driving classes. I only referred to your videos.
That’s actually amazing that you passed without any driving classes, amazing job congrats!
Wow I did not know you can take a test without any lessons took before that
Congratulations to you! 👏
@@HonkerzGang I guess you can, either you'll have to take driving lessons from instructor or anyone within your friends/family who has held a full UK license for more than 3 years.
Well in my case, I was already driving for last 9 months on my International license in UK and 10+ years in India, and followed Richard's videos for technical stuff. My basic driving skills were already developed, with his videos I learnt the British driving technicalities.
That's fantastic to hear, thank you for watching and congratulations on passing!
@@HarshSinghtheHSB If you have 10+ years driving experience in India, you basically can drive anywhere 😅
Sir I passed today my driving test.
Thank you very much for your help and support.
May God bless you. ❤️
👏 👏 👏
@@Apex-pred thanks dear
That's fantastic news, congratulations on passing!
@@ConquerDriving thanks sir
I love how your car looks brand new even though it has 189,000 miles.
what taking good care of your car looks like
I'm no car mechanic so take this with a grain of salt, but the 1st gear run probably wasn't as bad for your engine as you may think since the engine was under very little load. That's why you got decent mpg even at 5.5k rpm. If you where towing 10,000 lb at that same rpm and up a grade the engine would have to use much more fuel to sustain the engine speed and that could possibly cause enough pressure to blow a head gasket or overheat. As long as your engine had its oil up to temperature and good valve springs the high rpm theoretically shouldn't be a problem for the test you did assuming no weakened spots in the engine.
This is true, but everything (alternator, AC pump, cam belt, pulleys etc) was spinning much faster than usually for a longer period of time than usual. I'm sure it's fine but didn't feel good.
@@ConquerDriving it is made for it, thats why you have a redline lower than your car can handle, alternator and ac pump usually turn off when overloaded.
@@jordanvalenciamanuelpillai2917 Exactly. If the cooling and lubrification systems are well taken care of, the car should handle it all just fine.
Guys don’t foget he is an instructor. He still needs His car and has more mileage on a Vag group car than more most reliable car do.. he know what he is doing.
The engine won't break but the wear is accelerated. Any prolonged high rpm will be felt down the line. No matter how much oil and coolant u use there will always be friction and heat.
This car keeps impressing me! The fuel efficiency is par with modern standards easily.
Yes, the latest petrol manual cars have not improved much when it comes to efficency over the last 10 years or so. It's hybrids that have moved efficiency forwards. At least that's my experience.
@@ConquerDriving even worse, latest engines have pearticulate filters in them, which lower fuel economy.
EURO-5 TSI probably are the best there'll ever be in non-hybrid gasoline engines with good fuel economy and enough power...
@@ConquerDriving Yes its kind of nuts that many smaller Hondas have been getting 40 mpg highway for 40-45 years. The only difference is that my curb weight today is more and the interior space is better. I guess we can believe what they say about thermodynamics that ICE cars are at best 30% efficient. We can probably surmise that in the US economy is not as paramount as it is in other countries because they either have smaller cars or diesel with it's intrinsic better energy/higher torque.
@@jamesmedina2062 A 40 year Honda that gets 40mph highway is a 70hp tinbox with bicycle tyres, there are 2 ton 300+hp petrol cars today that can get 40mph highway, while blasting the automatic air con and massaging your back. Don't compare things that are incomparable.
@@BigUriel Not possible man. The way engines are designed, the powerful 2.0L turbocharged engines capable of pushing around 4000 lbs have no way of achieving 40 mpg mixed driving which is what matters. The GTI has nice gearing and can achieve close to 40 mpg on the highway only. But it is not 4000 lbs. The curb weight is like 3200 or 3300. And besides the heavy weight most vehicles are double the height of traditional cars so they have far inferior aerodynamics. So for all the fantastic computer processing, timing adjustments on the fly, and thermodynamic advances fuel economy is not that good. Look at the vast majority of vehicles today and be honest please. The trucks get less than 20 mpg and the bigger cars and SUV get mid to high 20's. Slow highway driving on flat ground doesn't count. I can get 55 mpg on flat ground at 55 mph. My typical 75 mph in town highway and the hills here cause me to get 37 mpg and thats with 1.5T and 2780 lbs curb weight in car with the benchmark for engine efficiency.
Thanks, great review. The issue with higher gears is that if we have uphill, the slightest slope affects fuel economy adversly
yea this video largely ignores that aspect of this but it is important to note that using a higher gear like this for better economy is only applicable when cruising on near level ground because in such cases the cars speed can be almost entirely maintained by momentum and the engine isonly required to provide slightly more power than what is needed to keep the internals spinning
No. The injectors will not spray more fuel into the engine due to the Lambda and the amount of air coming in. It's just like biking: you have to select a lower gear not because you use more power but because you are not able to deliver the torque. Power = torque x rotational speed. Power does not change, so you have to increase rotational speed to lower the torque.
The energy requirement is the same. You have to raise the potential energy of your vehicle when climbing.
If you cannot generate the amount of power required, shift down. That's what the gearbox is for.
I loved the nuanced summary that you gave at the end. It's important to note that it's not just the engine that gets damaged by under-reving; It's also everything else between the engine and the wheels.
When it comes to gear choice and fuel efficiency, you're trying to balance 2 things: pumping losses and thermal efficiency.
The faster the engine spins, the harder it has to work (the more power is required to overcome the act of) sucking fresh air in and pushing exhaust out of the combustion chamber. This means the lower the rpm, the less pumping losses there are, and the higher the rpm, the more pumping losses. More losses is bad for fuel efficiency, so lower rpm is good for fuel efficiency.
Does that mean the lower the better? Not so fast. There is also thermal efficiency of the engine. The engine has an easier time extracting kinetic energy from the burning fuel at some rpm rather than others. At very low rpm, the pistons are moving too slowly to absorb the energy released by the burning fuel, and at very high rpm, the pistons are moving faster than they can accept the energy, so a medium rpm has the best results for fuel economy.
There is also throttling losses in a gasoline/petrol engine, and when the throttle is mostly or partially closed, there is some restriction that the engine must overcome to pull in air, so very low throttle inputs are also not great for efficiency.
When you combine all of that, the most efficient rpm to use depends on your engine's thermal efficiency curve and how much power you need at the given moment. If you need a small amount of power, typically you want the lowest rpm the engine runs smoothly, typically 1100-1300 rpm or whatever your highest gear allows. If you need to make a lot of power to accelerate or climb a hill, you want to go into the thermal efficiency band a little more which varies by engine, but most reasonably sized engines are going to be most efficient between 2000-2500 rpm. Going faster than 3000 rpm on a normal engine is wasting fuel no matter what, but sometimes you just need or want the extra power.
You also want the throttle opening to mostly open if possible. You don't want it open fully (accelerator to the floor) because then the car's computer might start asking the fuel injectors to make the engine run rich which isn't great for efficiency either.
What you have written is how I understand it works. Although son cars keep fully open throttle and uses the intake valves to control throttle.
Modern engines cannot run in open loop, so will never run rich at constant speed
THANK YOU FOR TAKING TGE TIME TO DO THIS TEST. IT HAS HELPED ME VERY MUCH!
Thank you for also showing different measurements on mileage! Keep up the great work
I passed my test back in december 2018, but i’m gonna sub purely because the stuff you post is interesting :) I’ll probably end up learning something new
Thank you so much Richard for all your wonderful videos, your videos are the main reason I cleared my exam on the first try. There were things that my instructor failed to tell me but through your videos and your plain explanation, it was made very clear what I was doing wrong and how I could correct it. On YT I have only seen your videos that tell what happens if you do something wrong instead of only telling how to do something like 99% of other driving videos. Cheers.
It's actually good for your car to do some high RPM runs now and again, it's a good way to clean out the exhaust and cylinders.
Lugging your engine puts strain on all the parts and kills it quicker, accelerating from 20mph to 70mph in 5th gear all the time will kill it pretty quickly.
Yes. I love letting my Honda with 6.2k redline sit at 8k rpms for hours at a time. Runs like it never has before.
-sarcasm
Seriously though. Nothing wrong with doing some quick accelerations, if you're not pushing to rev-limiter every day :D. The autos love to rev out a bit.
@@Owlbolt
"... if you're not pushing to rev-limiter everyday."
>Your Honda ownership license has been revoked<
;P
The good 'ol Italian tune up.
Complete bullshit, running with low revs (but still above idle) does not put it under strain, the piston speed is at its lowest and torque is also low. There's nothing wrong with revving the engine, but carbon build up will happen either way, becaus even if you don't think about it, you have tubput the engine under load now and them, to climb a hill or pass someone on the highway. Use some fuel additives to minimize it a little.
Not valid for engines with high valve overlap because of knocking, but in this case you will definitely know that something isn't right.
Great observational experiment. I never properly drove a true manual but can appreciate the thought a driver must make in regards to gearing, flexibility and safety.
In my old diesel DSG car it was fantastic how low I could get my revs with the car handling it fine. I always watched the KpL info when doing diferent gears on different grades in manual mode gears. The observations from this video match my own. Diesel is a fantastic choice for economy. MY current turbo petrol has a dual clutch also, quite a bit of pep, but gosh I miss diesel economy and torque creeping.
Thank you for going so far to give us good information. I appreciate you so much
Really needs to be repeated at a higher speed (at a test track, old airfield or something). Above a certain speed your car's mostly fighting air resistance, meaning higher torque required to maintain speed. Curious to know if results are different at 60MPH
I would be interested too.
No. Lambda is is master over the engine - in closed loop- and fuel injection. So: the lower the revs, the less air goes into the cilinders, the lower the fuel intake.
i'd also like to know how speed relates to efficiency. i get better mileage at 45 mph than 30 mph but above 60 it appears to start going down again. i'd also be interested in the difference between gearing on the same car, for instance my automatic vette has much longer gears than a manual one so i wonder how much better mileage i get
The results wouldn't be different at 60 MPH.
The only way they can be differrent - if the car goes steep uphill at 60 MPH. Then 5th gear may be slighthly more economical.
The cruise control on VW MQB cars (such as this SEAT) is set for best economy, with 7 speed DSG it would shift a gear lower when going uphill at high speed, from 7th to 6th, even though the engine is capable to pull the car uphill at 7th gear.
If there's no special eco mode in DSG (just drive and sport) it would keep one gear lower without cruise control, to give the driver a bit of acceleration without downshifting, if needed.
I'd also like to see the test repeated with the same style car, but with different engines.
I passed my test over 20 years ago but am still learning new things thanks to your channel
Thank you so much for burning your fuel and letting us know how to be economical. I love your subtle comedy.
I always try to be in "right gear", the higher the better. I've a hatchback with 1000cc three cylinders engine, kinda family car, nothing sporty.
Few days back, I called a driver and let him drive. He used to change gears really very late. Like he goes, 25mph with first, 35mph with second. I hated it and took over the controls. It was eating me up from inside, not just because it was consuming whole lot of fuel but also because I couldn't bear what my engine was going through.
I know, that is fine if you're in a race, wanna speed up as quickly as possible. Performance over economy!
This videos, on your channel are great!
I have my license from 2016, but the learning never stopped. Actually, there was much more learning going on, regarding driving, from your lessons then from my driving instructor or any other driver or circumstance.
Thank your for your effort and dedication!
Passed my test today with 2 faults. Your videos have been a tremendous help during my journey of learning to drive. Thank you.
That's fantastic to hear, thank you for watching and congratulations on passing!
oh my god, km/l? on the internet? i can't belive this is the first time i don't have to do conversions manually on my head! Thanks a lot for that one!
i have done the same tests with my 2022 suzuki swift with the k12N engine. I have seen that when going uphill, sometimes using higher gears causes more fuel consumption.
and 99% of the time the gear the car wants to use is the most efficient.
Optimum Gear with Optimum RPMs
great video much much usefull as always ! i already got license but i still learn new things by watching your videos.
Cheers for including the results converted to U.S. and metric!
A question I didn't know I wanted answering at the back of my mind, has been answered.. thank you! Might I add, well explained and presented
Make sure to drive off from a standstill in 6th gear for optimal fuel economy!
(And let's not forget outstanding clutch wear)
The optimal drivetrain for low speeds is the Toyota HSD, just having the engine run for a few seconds at its most efficient point and then using the electricity fed to the batteries to move forward
That would worsen the fuel economy. Accelerating should be done at at least 50% throttle and lowish rpm for peak efficiency.
Am in love with how pass your points across, keep it lit
You should also mention that this is for petrol mostly. In practice, higher gears in a diesel CAN and DO consume more fuel if you're not in the correct gear. It's because in a diesel the car suffers way more when out of ideal gear than petrol. From my observations, let's say we're going 50 km/h, optimal gear in a 6 gear manual is probably 4th. 4th and 5th are going to roughly give you 3.2L/100 km if cruising. But shift to 6th gear, if the car doesn't like it I have seen it go to 3.5 in practice, and 4 or even 5L/100km for any tiny bit of acceleration.
I could keep in 4th and it's also going to go to 5L/100km for acceleration, but this is going to happen over a shorter period of time. I could go to 3rd gear and then it will go to 7L/100km for an even shorter period of time. Going to 3rd will be better if you're going slightly uphill, staying in 4th will be better on a flat surface, especially with the turbo most diesels have.
Obviously, when above the ideal gear it's not going to scale like 1st and 2nd gear, where the computer may show anywhere from 30-99L/100 km, but you should not torture the car if you have a diesel since they're more sensitive about revs.
Depend on the gear ratio too,Skoda yeti diesel (manual 6 gears) of my uncle 50km/h in 5th is ok.
With my manual 5 speed audi A4 (2003) 1.9tdi,i can cruise at 50km/h in 5th gear,
the engine still happy,take time to pick up speed but,fuel efficiency is there.
Form various cars i have drove,70km/h a good mix between fuel saving and resonable speed,90km/h ideal speed on highway for not be too slow and manage fuel saving (trailling truck helping too).At 100km/h fuel saving start to be bad unless following a truck,above 110km/h fuel saving is none
I never knew about this, it would be nice if he did a comparison for diesel cars. I never owned any diesel vehicle so I wouldn't know too
@@waynelau3256 You could probably do it in a 10-12 speed automatic with paddle shifters. If the ideal speed is 4th lets say, you put it to 7th or 8th. Of course, you're not going to have much torque, sure, but you'll likely need more gas than in lower gear to cruise at the same speed.
The thing that is important is to exit the most efficient RPM range. You could probably see it if you try to start from 3rd gear (although unsure if you'll have enough torque, a diesel can start from 4th even so it's easier to see).
You would think that it's all the same, you try to spin the wheels, your additional spin is converted into torque and you take off, just at higher revs... But at higher revs your engine is less efficient, so there is less work you can do, and that means that for the same work you expend more energy. In diesels you lose efficiency after roughly 2.5-3k revs and it's easy to see. In petrol you might need to go above 5k depending on the engine. Some petrol engines redline at 5.5k already so it might be difficult in practice xD
@@Milecarful thank u for the knowledge kind sir. Still so much to learn about all these
interesting, i would think the opposite would be true
I have a 1.6 mini one from 2006 and I can use 5th gear at 30 just fine and it revs to abt 1300rpm on a flat road. Using 5th when possible instead of 4th and taking my foot off the pedal and coasting towards roundabouts and downhill got me from around 44-45 to 59-60 which has saved me tonnes in money as u would expect. Always happy to see videos of actual results like this. Really useful thanks so much!
For some reason, I'm always surprised at how good the fuel economy of european cars is. Here in the US, getting over 40 miles per gallon (US) is considered really good. Most cars I've seen tend to sit in the 20-30 range.
This economy is at a steady 30mph though. If I was stopping and starting as usually my economy would likely be around 40mpg imperial.
@@ConquerDriving Yes, you're right, but that's still higher than I would consider 'average' here in the US.
You do have to keep in mind that an American gallon is different to a British gallon :)
A gallon in the uk (imperial gallon) is larger than a us gallon so naturally cars here would do more miles per gallon due to having larger gallons
The fuel is cheap, having a Camry with gashog V6 - not a biggie. :)
In the 90's I drove for 10 years my 1,3 Toyota Starlet like this (5 gears only though) and there was no problem with the engine even after 163.000 km, when I sold it. Gota a soon as possible on the higher gear and "listen" to what the engine told me.
Great Video!
Finally passed today after my 3rd attempt with 4 minors, thank you so much for your videos! Your tips were invaluable and no doubt helped me pass :)
That's fantastic news! Thank you for watching and congratulations on passing!
Excellently done. The only comment I can think of is economics. If you are conserving gas for cost savings you might want to weigh that against the potential greater engine wear of using too high a gear (and thus very low revs.) At what point do gas savings get over come by the cost of an engine rebuild? Hard to calculate.
The problem isn't in cruising at low revs, but when power is needed at low revs. The term I've heard for that is "lugging" the engine. This is especially hard on turbo-charged engines. That said, if power is needed, its easy enough to downshift, apply power, then shift back up for cruise.
Bare in mind my car has 190,000 miles, I've owned it since new and use low revs a lot, it's a learner car so slow driving is it's day job.
I really like your videos, I appreciate how transparent and evidence-based your approach is.
As well as your driving tips, I feel like I'm learning how impressive that 1.4TSI engine is!
Thanks for the effort! For what it's worth, I'm keen on economy when towing a caravan with a Passat Estate 2 litre TDi 150PS. Definitely better MPGs in 5th than in 6th (top) gear. I get around 38MPG at 45MPH cruising, over a full journey, without slip-streaming. However... I have adaptive cruise control ACC which is basically a radar connected to the throttle AND BRAKES. If I can tuck in behind a big lorry, at typically 55MPH for long stretches of the journey, I can get 40-43MPG over the trip. Without the caravan, 65MPG averaged over a tank (with mixed economical journeys) is achievable. Given the 66 litre fuel tank, this is more than 900 miles range.
I want to add that direct fuel injection and port fuel injection behave very differently at very low rpm. Normally direct injection has a major advantage over port fuel injection in terms of efficiency, but at very low rpm (under 1300-2000 depending on the engine) direct injection will struggle to mix the air and fuel together well enough, resulting in poor efficiency, whereas port injection has excellent fuel mixing at the 1000-2000 rpm range so this test will have a different results if done on a port injection engine.
Some manufacturers use port and direct injection
@@thepurdychannel8866 While the cost of such systems is higher, they do have the best of both worlds. They all rely on a combination of direct and port injection at low rpm and by 1800 rpm they almost all rely strictly on direct injection.
The car I used has direct injection.
Didn't know that I seldom go over 2000rpm.
Thanks for answering the questions everyone has but doesn't bother to look for an answer for them!
Definitely depends on the car, my 63 plate Diesel Focus can handle 30 in 4th, but unless the road is perfectly flat and there’s no traffic it’s better off in 3rd.
Ends up being more efficient if there’s any hills, and definitely more flexibility.
My wife is actually learning to drive, and her instructors car is better off in 4th at 30. Good learning for her to get used to other cars gear ratios as well in this case.
Agreed, actually my car can cope in 5th gear rather well at 30mph just a needle under 1500RPM, it can even do 25mph in 5th gear although the engine does growl and ask for a lower gear at that point, the gearing's quite high on my 1.6 petrol Focus.
"63 plate" just write 2013... it's shorter and non-uk viewers understand
My dads car ( Ford C-Max 2014) cant do 4th at 30mph. When i get above 55kmh(dont know exactly mph) i shift into 4th. Its a diesel btw which explains that.
Appreciate the effort you put in to do this.
Did a similar test with diesel, Ford Smax 2.0 TDCi 140 and Peugeot 5008 1.6 e-HDi EMG.
Not using all gears like you did though, but only the more appropriate once, 3,4,5 or 4,5,6.
1 stretch flat at 40 km/h CC
1 barely uphill at 50 km/h CC
1 uphill with sharp turns, 50-60 km/h non CC. So steep that going down, you can neutral-coast and maintain your speed around 60 km/h.
Don't quite remember the differences, but I was surprised how high they were, and how low you could go with rpm.
Basically my numbers pretty much match your numbers as far as I remember.
And the highest/heaviest gear gave better consumption as long as the engine was able to make usable power. Especially in my "steep" uphill-test they struggeled in 6, especially the higher geared Smax, as in one turn you'd want to go at around 40 km/h. Tried to modulate throttle to not have them struggle too much, but took long time to build speed again and that really hurt consumption.
Tried 6 with 5 in slow corners, but there wasn't much in it compared to just staying in 5.
Done that one turn quick enough for 6. though, and that would be the winner.
The full use at second gear is nearly half the fuel usage at 1st, when the rpm is about half aswel, funny that.
At lower rpms the engine throttle position becomes more relevant.
Cool video, really enjoyed it.
Really interesting video. When I used to drive a manual, I was eager to get into a higher gear as soon as I could (not that I realised that I was saving fuel). However, and as you are probably aware, there are many variables which this video didn't really take into account. Wouldn't it be good if there was some kind of website that published figures which took into account all the variables for a range of diferent cars.
That would be intersting, but generally, if the revs are low you use less fuel, if the revs are so low the engine struggles then you don't save fuel. I think other variables would make a small difference, for example - low revs vs higher revs at cold temperatures.
In general, you want to open the throttle and regulate the amount of power by choosing an appropriate gear if you drive a manual.
I've always wondered this. Great test, thanks!
A minor point on older diesels (2000-2010 ish), most of them tend to run quite lean, especially throttleless designs (like PSA's older 2.0 HDi engines), so they tend to be quite good under light load even at higher revs. They also have a fairly narrow band of efficiency (the HDi sits around 2k rpm, ±250). Running slower results in dirty combustion under power, clogging up basically everything, and running faster ups parasitic losses significantly, though the odd Italian tune-up is still justified.
With most diesels, it's still best to accelerate under nearly full power. This is because they reach their peak thermal efficiency under full turbo pressure (this is where older unthrottled designs tend to edge out - full pressure grants peak efficiency, but that's not necessarily all the power available). The same holds true for petrol engines too, but the efficiency gain there is smaller and, whereas in a diesel, this outweighs parasitic losses from within the engine, in a petrol engine it doesn't.
And in new diesels it's all different too, NOx emissions regulations preclude lean combustion to the extent possible with the older models, so they behave more like petrol engines.
Right, i remember getting a new company car in 2014, Fiesta 1.5cdti, and being amazed how easily revs to 5k and the torque feeing so linear from 1.5k to 4.5k rpm. Funny thing, modern petrols like 1.33 dual vti from Toyota pulls at low rpm like a diesel!
@@stefanr.3495 Yeh, turbos will do that
on my DSG 1.9tdi I will usually give a bit more throttle when the gear increases. Especially from 3 to 4 th gear it can shift too early
@@FSXgta The 1.9TDI is a pretty neat example actually. From an owner's perspective, as long as you don't run it on supermarket fuel, it will probably outlast you (the DSG... not so much). But more importantly, it took 30 seconds to find a brake-specific fuel consumption (BSFC) map for it. (x-engineer.org/wp-content/uploads/2017/08/Brake-Specific-Fuel-Consumption-BSFC.jpg)
On the X axis is engine speed (rpm) and on the Y axis is cylinder mean effective pressure. Inginerd speak for torque. The contours represent BSFC and for fuel efficiency we want to keep that one as low as possible for the required power.
The dotted red line on top is your dyno torque curve. Note the flat bit in the middle. That's a limit imposed by the boost controller (for many good reasons), but it's also the ideal acceleration range in this case, per the bsfc map.
Ideally when accelerating you want to sit at about 80-85% of max. torque and around 2200 rpm, and presumably VW were intelligent enough to programme that into the DSG's software. Once you're up to speed and off the throttle, your torque demand goes down, thus the rpm ought to go down too, otherwise fuel is being wasted.
What you say about adding more throttle makes perfect sense. In higher gear you need more torque to make the same power, plus at higher speed you need more power to maintain acceleration anyway, so naturally when the DSG upshifts the car will need more throttle.
If you look at this map though, you can see what it's doing. By forcing higher torque at lower rpm under moderate acceleration it's pushing you up into the engine's efficient region, where it makes the same power with less fuel.
If I'd been the one deciding the logic though, I would have made gear changes as seamless as possible. Given that these engines essentially run under FADEC (look it up), there's nothing stopping the thing automatically increasing engine output to maintain either constant power or constant acceleration (assuming *moderate* acceleration). With all the pointless "customisation" options they offer, you'd think someone would have thought to let you set preferences for important stuff like throttle logic and responce.
I watched the whole video. I loved it. Learned a lot about fuel economy. Don't even have a car. Glad no one took the racket.
Thanks for the awesome Test!
(Not a mechanic here but:) I believe the 1st gear run wasn't that bad for the car, considering the high rpm you get, when driving high speed.
I regulary drove an old renault megane 1.6 16v on the Autobahn with about 190-210 km/h (~125mph) (should be around 5500 rpm) at which it would get much more stress on the components, i guess, however, this thing runs perfectly fine since 2006ish. No problems at all.
Frankly, most of the time, i weren't exceeding 160km/h (100mph) because i gets quite noisy then, but sometimes, when theres lots of space and little time, i went full throttle for about 5-10min at a time.
The fuel consumption rises exponentially at that speed, therefore i don't often drive like that, nowadays.
This is very useful video. Make video on what minimum and maximum speed gives highest fuel economy in normal condition.
Very glad to see a video showcase this bit of (what seems to me like) common sense. As long as you're not lugging the engine, lower RPM always = less fuel.
I too stick to 5th at 30 in our 2011 Astra. Most of the time I just get to speed in 2nd and then just jump to 5th, as I'll only be in 3rd or 4th for a few seconds if I bother.
Obviously that's if the road is clear ahead to be able to reach 30 quickly.
In my BMW E46 I swapped the diff for one that is slightly longer. Dropping the RPM by roughly 400 rpm at high way speed (from 3000 to 2600). The gain in fuel economy is noticable for sure.
My main tip for fuel savings (I realise this is a little off-topic) is don't accelerate to the place you're going to start braking. So many people accellerate to off ramps and then stamp on the brakes to scrub off the speed they've just paid for. Likewise the constannt accelerate/brake style of urban driving so popular with teenagers.... yes we all did it, but its a good habit to break.
So ends the second sermon.
Agreed. I can always tell who's in an automatic because they don't care to bother coasting
That is actually wrong advice. Slow accelerate does not save money.
@@boobo It's more so don't get a bunch of speed just to brake it - instead of going 60 -> 0 at the lights, go 40 -> 0, you're waiting anyway.
@@boobo You probably misread it; it doesn't say accelerate slowly... it says don't accelerate pointlessly. IE: "Don't press gas AND brake" which is in fact great advice.
This way you save not only fuel, but your breaking pads/discs too!
I like your thorough methodology and presentation with US units included. You have a new subscriber for sure.
I drive a 2012 Toyota IQ with the 1.3l petrol engine mated to a CVT, have done for 10 years and 200k miles, so the idea of individual gears doesn't apply to my car, but the behavior of the computers that control both the CVT and the throttle seems like they want to do exactly what you're suggesting here. There doesn't seem to be any problem with the engine pulling me along at around 1krpm at neighborhood speeds and around 2k to 2.5k at US highway speeds when being easy on the throttle in eco mode. It idles at 500 when I come to a stop, which felt a little rumbly and worrisome when I first got the car, but 10 years in it's just normal. But basically the computer is setting up my CVT to be in a similar ratio to where you're at in the 5th or 6th gear test depending on the grade of the hill, and I'm assuming Toyota's engineers spent a lot of time working out the precise efficiency curves so they can plug in just the right numbers into the computer to maximize that MPG number for marketing purposes, so the fact that it all lines up based on your data here is just proof in the pudding. I'm assuming probably any other small 4 cylinder made in the last 10 or 15 years can probably do the same.
I did a similar test to this, only with highway driving and managed to find that between 4th and 5th at 70mph (3,000 RPM vs 2,500 RPM or thereabouts because my car has an analg tach) and I managed to get 34mpg in 4th and 51mpg in 5th.
I get 70 mpg at 70 mph in 6th gear
@@TheSuperBoyProject what's the car?
@@razor_ramon_ it might be a bicycle with that consumption
@@mevio4665 ahahah
Don't know why but when I'm driving in steep hills, I always try to find the upper most comfortable gear for the engine (if I press the throttle harder and the speed doesn't increase, then I assume that I am in the wrong gear and downshift) and try to keep it in the RPM where the engine develops peak torque. In my mind, by keeping in peak torque RPM, the engine will produce the maximum force so I won't use as much fuel as it would in other (perhaps upper) gear when going uphill. Nice video !!
I'd also like to see a video like this comparing the same revs in different gears.
Dropping in to say thank you for these videos! I passed my driving test with only one minor (or something like that, the Finnish system is quite different) today. Your videos were really helpful even though I did have to adjust slightly since we drive on the other side of the road, and Finnish roads are less of a wild west compared to the UK somehow.
That's great news! Congratulations on passing!
I have my Finnish driving test in about 2 weeks, hope I pass as well
I've just moved to a six speed gearbox, and it's always telling me to change to 4th when I hit 30mph. I feel I've had to completely relearn my understanding of acceptable revs ect. Interesting to know you were taught to sit on 3rd when learning, I think I was too!
key is that a hill or acceleration will require a quick downshift to 3rd but for steady pace, 4th is just barely sufficient unless also you are at sea level and very flat area.
Another great video my friend. Thanks a lot! I'm learning a lot from you.
I tend to leave it in 3rd at 30mph because I'm fastidious about keeping to the speed limit and I find that 4th gear creeps up more easily if you're heavy-footed. I might try using 4th and laying off the accelerator a bit based on this.
That being said, mos of the time I ride a motorbike that gets 150+ mpg so not much of a worry.
Thanks for your videos you've made me better driver than my driving school.
And it is also nice to watch you, you have some kind of Jim Carrey vibe tbh
Richard fantastic video as always. Can you do the same with the diesel engine? I am curious because the diesel engine does not have the throttle valve, in theory keeping the rpm very low is not good for diesel engines because of the egr system and the fap filter I think.
Thank you for the suggestion, I may do in the future.
@@ConquerDriving if you do, just make sure not to do the 1st gear run in a diesel 😂
At low rpms, you’d likely be loading the engine which would hurt fuel economy because the engine needs to inject more fuel to maintain speed. Under such load, the EGR should also be less or completely inactive.
EGR might reduce the lifespan of diesel engines, but they should have little effect on fuel consumption.
Great video. My advice keep your revs under 2000 rpm. In all gears. Also get to top gear as fast as possible. If you can look ahead, consider coasting up to traffic lights. Anything to lower revs. Basically the heavier your foot, the more you spend on fuel.
Fuel economy is usually directly correlated to how much you put your foot down. Even if you are on 1000rpm, upon flooring it, the car gets the message that you want to accelerate and will pump lots of fuel to compensate for lack of horsepower at low revs. However, most cars especially in steep hills or under heavy load will struggle with 1000rpm. So it's best to build momentum before climbing hills and ensuring the car is at the rpm where it's most efficient during the climb.
you are right on efficiency but wrong on "will pump lots of fuel to compensate". Power is not increased directly by adding more fuel, it's increased by first opening throttle to let more air in, and it only add more fuel when the air flow has increased.
@@francoisloriot2674 Many modern cars have the option to display live consumption that refreshes every second or so. I noticed that if the car is on low rpm and struggles to climb a hill, it will pour more fuel. For example if I am at 2100rpm on a turbo diesel engine, I only need to press the gas pedal slightly and get decent power with good efficiency (eg 3.5lt/100km), but if I am on 1100rpm that value always increases to something like 12.5lt/100km even with little throttle input. If I fully depress the gas pedal while on low rpm it can go over 20lt/100km, especially on lower gears plus the engine can be damaged by driving with too few rpm. Bet it's some sort of system that shoots more fuel to prevent stalling.
@@orm6922 again, it will not add more fuel (unless the conditions call for a richer mixture). if you want the details: to prevent stalling it will open the throttle blade a bit more, the Mass Air Flow sensor will detect an increase of air, ECU will then increase the duty cycle of the injectors to keep the air/fuel ratio. What some people call a 'gas pedal' (true name is accelerator pedal) just cause more air to get in. The ECU does the rest. Yes, in the end you will have more fuel, but all I wanted to say it's start by adding air and not fuel.
My highest gear, 5th gear, drives at about 3k revs at 60mph, and 4k revs at 70mph, It's a very close ratio gearbox. It doesn't tell me my fuel economy but it does feel awfully consuming. Good video
What displacement? The manufacturers' engineers seem determined to keep the drivers out of lugging potential because that can cause issues. Higher revs in some 4-cylinder engines utilizes momentum to control the car at its highest gear, with say 130-150 HP whereas a GTI with 230HP in MK4 would turn at 2000 or even 1900 RPM going 60 mph since it has higher displacement and power.
Low revs are great in a petrol but man, in a modern diesel they can cause all sorts of problems with the assortment of filters they have, specifically the DPF and EGR are common faults. A friend has an automatic mazda 2.2 skyactive around 5 years old, and it keeps the revs low with the tonne of torque the engine provides and even though he does mostly long (50km+) journeys on the motorway, he's currently got massive problems with the dpf and cat.
Another thing is the Dual Mass Flywheels that tend to self destruct when people get remaps for fuel economy (which in a diesel just means more torque lower in the rpm band), massively more load on the DMF (an expensive part to replace) ends up burning all the potential fuel savings.
A personal experience, my dad has a remapped 1.9jtd which can pull with ease from 1800rpm in 6th, but it also destroyed the weak bearing in the infamous M32 gearbox which cost over 600eur to repair.
Amazing test!
Would be interesting to see the same test but going slightly uphill, to see how much increased resistance affects fuel economy in different gears. I'm pretty sure that at some angle 4th would be the best choice.
I'm sure that would be there case, I don't know of a quiet hill that's long enough to register an economy reading and quiet enough to make the test possible.
Thanks for doing this test. It pretty much lines up with my intuition diving a manual. I always keep mine in the highest gear comfortable. I once rode with a guy who always kept his near 3k rpm. I'd hate to be paying his fuel bills!
I would have liked to see a test in both directions for every gear, to average out slope and wind.
Near the end of the video I did some tests up the hill.
probably think its best.... " how the car is meant to be driven" of something
It really does depend on the engine and transmission.
In general, spinning the engine slower reduces parasitic losses, HOWEVER there are plenty of other things that come into play. For instance, when revving higher you pump a whole lot more oil throughout the engine, so as long as you don't sit in some resonance mode (for inline 3s and 4s, for instance) it's fine to rev. Thermal efficiency will also vary, with load as well as revs.
Manufacturers use brake-specific fuel consumption maps to determine optimum speed/load maps for automatic transmissions. This lets them sit in the highest possible gear when under very light load (as there's no power needed) and as soon as more power is commanded, those transmissions drop right down into a suitable gear where the commanded power is delivered most efficiently (unless you're in sport mode of course 😉). Humans don't tend to think in such terms most of the time, so recommendations tend to focus on being the safest option for "most situations" (i.e. including uphill etc).
But yeh, it really is down to each individual vehicle. My 650cc bike for instance quite happily cruises in 4th at 30mph, and can do so in 5th and 6th, but if I'm in 4th I get steady operation (some performance engines run rougher at low revs), excellent fuel economy and enough torque for "normal" steady acceleration if needed.
By virtue of it being a fairly high-revving engine (red line is upwards of 12k... and that howl! 😁), I don't imagine cruising in 5th or 6th at 30mph would be particularly healthy for it. 40 is fine for 6th though.
The other thing to take into account is air drag. At 30mph there's none. Not as far as the car's concerned anyway. Most parasitic losses come from within the engine at that speed, so your test results make perfect sense. It starts to become a factor around 50mph and becomes the dominant phenomenon upwards of 60. So if you repeated that test on the motorway, I would expect to see much smaller differences between 4th, 5th and 6th, though 6th should still win, even up a significant incline.
I have been driving these way long back when i become expert.
My instructor told me, no matter what dont let the engine jerked on higher gear, but always try to drive with low revs higher gear. And yea 106000 miles completed still my engine is rock and solid.
Two big reasons against eco-driving and avoid low rev/higher gear: 1) low revs cause stronger vibrations which translate to quicker wear and tear of car parts especially two mass flywheel installed in most diesel but also petrol cars 2) diesel only - dpf (particulate filter) to self-clean it needs higher burning temperatures and revs 1500-2000 for prolonged period of time, otherwise it will clog (which means stop for a car) and is quite costly to replace
educational and informative, as always. Cheers Richard !
Actually, more throttle opening means less pumping losses on a gasoline engine so you can only benefit from opening throttle. The reason you have better fuel consumption with lower revs is the fact that you have less losses in engine friction. However, every engine has a sweet spot in terms of revs and load where brake specific fuel consumption (BSFC) is minimised by design. By going in higher gears you're effectively going up in load and reducing BSFC. What you're testing is exactly that, same torque request but at lower revs and higher load 😃
This guy knows.
People dont know how friction plays a massive role at high rpm
Great explanation but in the last sentence you mean the same power request (to drive the car forward) remains the same at the same vehicle speed
Understood, now I’ll only drive at wide open throttle!
Dude I'm kinda jealous of how well your car is maintained. I own a 2012 Citroën C4 GLX 1.6 (Petrol) with only 125.000 km on it and it is way more negligenced than your Leon. I don't have a covered garage though, and I have to keep it parked under the sun all year round.
Thanks for the video and the explanation. I love these VW TSI engines.
This car is also kept outside, I do a lot of the maintenance that can be done with the car on the ground myself.
I would be interested to see what the best fuel economy you can achieve driving at 20mph, 30mph and 40mph. Politicians are forcing 20mph on us in many areas under the claim of reducing CO2. I think CO2 emission will be higher at 20mph for the same measured distance as the fuel economy will not be as good as a car travelling at 40mph in 4th (1:1 gearing) or higher over the same distance.
Very good point, I may do such a video in the future.
youre right. 20mph is polluting the air via the tailpipe more than 30mph. BUT those low limits are mostly in the city where you will do a lot of braking (brake dust). Also because of the low speeds the tyres wont be worn so much (rubber dust) and same with the street (asphalt dust). All in all in does not improve nor harms the pollution. The most important benefit is safety and noise.
@@anders2821 so you're a politician?
Really good video. You did the science so I don't have to. New fan.
I would love to see this on an automatic with a "manual" mode, because of the efficiency of the torque converter.
Many cars with a "manual" mode on an automatic are STILL automatic.
@@razor_ramon_ well, all cars with automatic transmissions with a manual mode are still automatic. Just some of them also have a duel clutch (more efficient)as opposed to a torque converter(less efficient).
@Geo’s radio & musical stuff yeah, they have gotten a lot better over time, but still they work off of fluid dynamics. In theory, the faster the torque converters driving impeller is, the more efficient it is to a certain speed. At the same time, the faster an engine spins, the less efficient it gets. So I would love to see where the perfect balance is between engine speed & torque converter speed where they overlap best for the best efficiency.
@@CameronCC I mean, they don't allow to shift when you want
@@razor_ramon_ mine lets you stay in whatever gear you choose, but yeah you're right, a lot of them that have "manual" mode just let you set the max gear that it will automatically shift to
Not many manual shift cars in the USA because people don't want them anymore. But both of my cars are manuals. I happen to prefer them. In those newer CVTs you have no way to control what RPM you're at at whatever speed you're going. The older traditional automatic transmissions you could manually select your gears but they might have only had three or four gears.
General rule:
Drive in highest gear possible with the least amount of accelerator pressure possible (usually, that's around 2-3k revs). That is also a good advice for driving when the road is snowy or icy...
That's just wrong .. better accelerate fast with lower gear to the desired speed than slowly shift gears in order to save fuel.
Its situational yes but in most cases just get to the desired speed then switch, ideal is at the 4-5k revs rather than the 2-3k, the reason automatic gears don't do it is because they don't want weak minded people to panic when they hear high revs and also want the car to be quiet, otherwise it would hurt the marketing of the car to the common plebs.
@@EliranC Exactly! You switch the gear down to accelerate and then switch it up when you resume cruise.
Most cars that I drove that have an automatic gearbox do the same.
I was taught to get to my highest available gear as quickly as possible, so long as it was a normal gear rather than an 'overdrive' and so long as engine was not struggling.
I was taught in 1970, using a 4 speed 1600cc and a 3 speed 3 litre.
This has worked reasonably well for me since, as you say listen to the engine.
Diesels can use much lower rev count, mine was red-lined at 6000 but I rarely went above 2500.
Essentially, use a lower gear to accelerate so you don't have to open the throttle nearly as much and high gear for cruising.
Always open the throttle as much as possible when accelerating.
Use a lower gear if you need to accelerate quickly, use a higher gear when you can accelerate slowly.
it's really important to remember that fuel economy is not all that matters. higher revs with less overall load per revolution may cause less wear and tear on the engine itself, reducing maintenance costs.
When you make the motor work harder at low rpms to run, you are opening ghe throttle all the way, reducing pumping loss. Making it mote efficient. Some cars have computers that will open the throttle and mess with fueling to minimize pumping losses without revving up
this vedio is amazing .keep up the good work👍
No matter what, as long as your car isn't "coughing", higher gear always yields better fuel economy.
However, do keep in mind that the engine is gonna wear faster because it's gonna need much more torque, which translates into strong mechanical forces in the engine components and drivetrain.
It's not so much of a problem for strong engines (diesels and large displacements) which were designed with keeping such torques in mind, but most small displacement such as 1L 3cyl. gasoline engines will wear a ton faster than you'd want them to.
A very interesting test that was methodologically carried out! Thanks!👍👍
great video, thanks! The only thing I just want to add to that is the turbo diesel cars change their behavior greatly under 1500rpm range. Driver would need more precise downshifts even in the slightest uphills.
ive been driving 6 years and ive done probably about 100000 miles in that time but i find your videos very interesting
Fantastic video!
I'm here in the USA and have a Mazda2 ( 1.5 direct injection, no turbo ) with a 6 speed manual.
Been hypermiling since 2007 and have noticed in all cars that lower RPM is always better.
This car loves 6th gear at 40mph / 63km/hr and i typically go full throttle from 1st gear to 4500rpm to 2nd gear 4500rpm and jump up to 6th gear and cruise at around 1100 RPM indefinitely.
Most hypermiling advice would tell you to accelerate slowly but i've found that more time at low load means slightly worse fuel economy.. so basically i hammer it from a stoplight and get into 6th gear as fast as possible... but don't redline it :)
The car has no engine braking so i tend to throw it into neutral coasting or needing to decelerate to a stop light... the car has skinny tires and is very aerodynamic so it can coast a very long distance.
End result of driving the car this way is 45.6mpg USA MPG / 54.76 British MPG.. the car was rated 35 USA MPG average and i do 50% city driving. It's impressive.
On long highway stretches if i maintain 60mph then i am seeing 60-70MPG US in 6th... quite amazing!
the car has no engine braking? I think you'll find it does. May not cut fuel, but it certainly would brake the car
@@James28R It injects fuel while coasting as seen on my scanguage II. No engine braking. No feeling of engine braking either.
I always liken it to riding a bike and consider your legs to be the pistons, there's always a right gear to be in for whatever forces are acting on you to slow you down whether it be ground friction, air friction, or gravity. The one main difference is that engines have flywheels of varying weights depending on engine size/type, a car with a very heavy flywheel will be much happier up an incline in a higher gear at low revs, or maintaining motorway speed in a headwind without needing much more throttle. It's a bit of a case of know your car. The tests done in 1st (and maybe 2nd) gear might be slightly inaccurate comparisons due to newer turbocharged cars having a different boost curve for those gears to put less stress on the transmission, particularly the case in diesels, and as the turbo is a fuel saving device it's not used to its full potential. All the same, a great video where there are so many variables. If your Seat was a diesel all you'd need to do is convince it that it's being tested for emissions and it would achieve +20% mpg and emit fresh air and rose petals out the exhaust ;)
😂
I've always used the highest gear possible, subject to drivability and the engine not struggling too much. Looks like you've vindicated my method.
I have a 1.9 Diesel, my son has a 1.4 diesel; same model car, same age and similar milage. At 30mph in fourth gear his engine is very comfortable whereas mine, with more overall power BUT taller gearing, sounds laboured. Despite that, in my car 4th is still more economical than 3rd at that speed. It’s all about the ratios in the gearbox and the characteristics of the engine - which with some turbo cars can be difficult to predict.
Awesome test, thank you for this 👍🏽
nice video - on most 30 mph roads i stay in 4th gear unless i’m going uphill, then i stay in 3rd so my car doesn’t struggle
I've been really curious about this for years, great video.
Does the presence of a turbocharger make a difference do you think?
I don't think so, my Mazda has no turbo and loves high gears as well. Modern engines have so many features now to help them run well at different rpms.
I would say, the exact amount of gas you are saving does vary car to car. For example, if you also had the same car from the video with the same specs, your fuel economy will vary slightly. This is because wear and tear. Also, for my fellow automatic drivers, the car is designed to shift up into a more fuel efficient gear when you aren't accelerating and it shifts down when it's to accelerate when you give it throttle. That means you can manipulate an automatic a little bit to shift when you want, for high to low pit the pedal to the metal, for low to high ease off the throttle.
Drove more than 1000km with a 6geared Hyundai i20, average consumption 4.7l/100km, I was blown away!
I drive an i30, I also got more than 1000km out of the 50l tank on several occasions :).
My absolute record was 920km in a Toyota Aygo (35l fuel).
@@svr5423 wow nice! Love these low profile cars. They do their job efficiently
Believe it or not, if you run your car at high revs but low load for a short run like this every month or so, it can help to clear some of the emissions control systems and carbon build up in certain components. More-so if you run some Redex or V-Power petrol through it. Useful to do before an MOT where they do an emissions check.
If you have any fuel consumption meter, you can read that in higher gears the consumption is lower. However other problems can occur. As the Power is Torque times rev, lower rews mean higher torque. As torque is proportional to the forces in the piston, it causes high friction and wear in the engine. Since i have a pluginhibrid, where i can not influence the revs, is see, that it runs on a safe side, especially when cold, at medium rews with low torque.