I echo what everyone else is saying, it is a bit of a lost cause for this season. The tutorials are great, and you will learn a ton. It can be easy to miss a step though, sometimes you need to go back a few to go forward again.
In the off season get some kids to learn Inventor. Once they start becoming proficient have them start designing chassis and drive train concept models. If they post them on CD they will be able to get some constructive feedback.
Thanks to 1323 there is a great online
CAD library
Utilize the existing models to start building some chassis.