Well, I don’t know about the car. I think only certain angles of a typical automobile actually offer protection. Other then that items like the windshield of heck even that paint can basically just chip into projectiles themselves, plus I don’t know of many people that get there cars with armored doors or anything.
I guess I would just take a second to evaluate my options, such as is anyone else around, or what could I maybe make it to in regards to protection such as cover, like a big cement block sometimes found around a light pole.
Lastly you could just walk away from your car, or be more direct with if they are following you. I mean if these people came to do you some real harm, its most likely going to happen regardless of what you do. Attempting to make it to your car could be bad as they might plan to use your car also... So who knows, sounds like a crappy place to be really. If you get the idea going in your head for sure that they plan to harm you, you can always take first strike I guess, with simple confrontation as a distance, preferably with maybe your hand on the gun or whatever, supplying the idea that things could go horribly wrong for whoever is coming after you might be enough to defuse the scenario, more so if they had some sort of plan that’s no longer seeming to work.