Hi iwkya, you might want to check out this:http://forums.cgsociety.org/showthread.php?t=571932
It's an incredible (and free!) plugin that assists in rigging cars. Also, it has the ability to let you drive the car, in the viewport, in real-time (with physics and collisions and terrain-following and everything)...and then bake the animation to keyframes.
I've used it extensively and I think it's terrific.