You can't directly move objects in tandem with physics. You use one or the other. It also looks like you haven't set up any constraints for wheels/chassis/etc? If you try to use things like c_move or my.pan with physics at the same time, you can actually crash your computer. I've done it before.

I'm also interested in how to set up constraints for vehicles physics though. No good examples exist, and the manual is pretty vague.