BeamNG - Importing collada shortcut. No material json needed.

If you like creating your own assets and importing into the game this is something you should know you can do.
I found a cool way to save space on your level folder as well as avoid the hassle of having to make jsons for certain exports. You also do not have to worry about baking texture maps and all of that. This is super easy.
If you wanted 1 object with multiple materials the same would apply. You can just assign another material from that folder to other faces, or join objects. Lots of potential for exporting things.