Unless things are hopelessly remote, it should be possible to get to a safer location before the car gives up. However, I'm not at all sure that they would give chase. Once the initial opportunity was blown, I think most likely response would be for the criminals to get as far away from the scene of the crime as possible. You are correct to point out that escaping the initial confrontation by using your vehicle as a ram, if necessary, doesn't insure that the situation will be safely resolved. Of course, that is true of any deadly force encounter. Being able to pull a firearm and return fire doesn't insure that you win a gunfight. Having a gun doesn't insure you'll be able to access it in time. Being an accomplished martial artist doesn't mean that you'll automatically win a fight. Just as the possibility of an unsuccessful outcome in a gunfight isn't usually touted as a reason to never use a firearm in self-defense, the possibility of an unsuccessful outcome from an evasive maneuver involving vehicle-to-vehicle contact shouldn't provide a reason to avoid any vehicle-to-vehicle contact in a deadly force encounter.