You're protected from impact weapons until they manage to breech your car. And if you have to shoot someone who manages to breech your car with an impact weapon, the damage to the car will provide evidence to the fact that they were threatening you with that weapon.
The car does provide some cover from gunshots, especially from the front.
Not in my car. You must be assuming that everyone drives large vehicles.
My vehicle I wouldn't not be reasonably protected from impact weapons. The width of my car puts my face, and my passenger's face extremely close to the side window. The follow through from a baton, bat, crowbar, etc. hitting a window would likely strike me, especially if I have a passenger as I would not have room to lean away from my window enough to ensure safety. It actually seems safer to exit my car, because you could keep yourself on the opposite side of the vehicle as the BG. Oh did I mention the convertible top? If it's down. NO COVER, it leaves me wide open, might as well be outside, where I can move, get behind cover, or run. If it's up, it's easily plausible that a heavy impact weapon could strike someone through the canvas, or even collapse the top and possibly trap people in the car. The hardtop adds a little more security, but not much. It's fiberglass, and not very thick, and it's plausible an enraged person could break through it with a heavy impact weapon.
Cover in my car, from gunfire, even from the front would be minimal. As I've mentioned, not much space to duck, and even if I could, the car is low enough that the BG could shoot directly down at me from the front, unless he/she was standing very far from my car and/or is extremely short. The way the cockpit is designed it does not allow someone to hide effectively. The vehicle was designed to comfortably seat 2 averaged sized men and not much more. And by 'comfortably' I don't mean luxury car 'comfort' I'm talking about 'sports car comfort' which means if you're about the size of a average size Asian man, you've got room for your legs, and not much more.
Again, this is assuming you're trapped. It'd just be plain silly, to leave your vehicle, if it was possible to drive away.