Nothing stops Chuck!
If I was the one driving the car and trying to run-over a bad guy that pulls out a handgun I would be ducking while my foot is still on the floor. After the thump I would back-up and drive over him again. No thump then I keep going and get clear of him and his gun.
Now, if the bad guy is trying to run me over I am moving out of the way and hopefully behind something that he can't drive-through. If that isn't possible then the only other choice is to start running towards the car and jumping, but if the timing is off then adios................ Shooting at the car isn't going to do much unless it is far enough away that the driver ducks and gives me enough time to move aside and hope the driver doesn't come back up to see that I have moved.
I still like Chucks method best!