Hey there, it is me again, as your reply I went on and started to play around with the vehicle, but the a request to you is, can you make me a small project where only the vehicle simulation is done or may be make a documentation for that. I know you said that it is all about the play of joints, but still I am not really understanding how it works.
Do you have any particular questions? Even if I created a piece of documentation, it would likely end up looking like a slightly expanded version of the VehicleInput class- it may not actually address what you have a question about.