Fixed a car once. It had been shot in the back. The round went into the trunklid, THRU it, into the rear seat frame, thru that, into the dash via the heater controls, and lodged into the metal framing of the dashboard. Well, we think it was in there, as we never found it.
I have another round from the same car that was retrieved from the door. The bullet went right through the door skin, and got stuck in the inner frame/crossmember (Intrusion beam). Having recently handled a 9MM round, I think this one is a .45
Another round penetrated the front door, hit the drivers leg and bounced at a 90 degree angle through the seat and lodged in the floor. It bent the snot out of the floor, and would have gone through that if there hadn't been a structural support right there. It actually penetrated the floor itself. It was the support that it was stuck in.
The seat was so blood soaked that we had to replace it, same for the carpet.
So to make a point here, cars are not bullet proof. only the engine block, and the trans case is. You would also be protected by the wheels, so long as they are not aluminium, spoke wheels. Those have large gaps of no protection.