If I were you I'd learn as much as I can from the existing setup scripts but to be honest, if you really want to understand the mechanics of setting up a car, just experiment as much as you can with all the variables and possibilities until you really understand how each function affects the car physics. Code and test and observe, alter code and retest and observe.
That sort of understanding (i.e NO SHORTCUTS) will give you a solid foundation to move forwards on and will inevitably produce a better end result. Yes its going to take some time but it will always be worth it in the long run.