you know whats strange? i was thinking about making something similar to this, with particles and gravity, but my comp was laggy and i didn't have the patience . But this is awesome, im glad to see that it works!
the only problems i have with this are the exploding wheels, and the way the car feels 'squigy', crashing into a wall just squashes the car and it bounces back. Other than those, this is a very good model!