NFS Carbon how to make extra cash using Free Roam Challenges

After playing this game for a good while since I’ve not played in ages I found a slow and probably useful way to earn cash after you beat the game and it’s useful if you need to buy a new car or upgrade them I’ve explained about this and don’t know if anyone else thought of the same so you have to head between billings district and kings park in downtown Palmont and wait for a rival racer to race you then win the race to earn $1.000 keep doing this and also mark it down on paper to keep progress of the money your making this is a slow way to make money after beating Darius but I highly recommend it and also helps getting some reward cards aswell and I also show some of the crew which I highly recommend I hiring any questions let me know any negative comments will be removed and blocked
Castrol Cash $10.000 enter the code in the main menu only works once per profile
PS2/PS3: Down, Up, Left, Down, Right, Up, Square, Triangle
Wii: Down, Up, Left, Down, Right, Up, 1, B
GameCube:Xbox/Xbox 360: Down, Up, Left, Down, Right, Up, X, B
PC: 5grand5grand