How do you bulid a mousetrap cars?

Answer 1

Generally it is done with a single drivewheel that is connected to the mousetrap so that while closing, the mousetrap will spin the wheel.

No modification is allowed of the mousetrap mechanism, however you can cut off the excess wood.

I would suggest using CD's, theyre lightweight, spin easily, and have pretty good surface area to work with. A bit of rubber stripping on them or something similiar will give them grip.