This is why you should carry a S&W 500, so if this day every comes. You can whip it out and unleash it on the engine...
I thought about this, but very very very very very rare this would happen, way more likely to get attacked by someone than a car coming after you.
I would walk behind another parked car/pole so if the car hit it he/she would get damaged by it.
If I was in a open road with no poles/cars to use for cover I would defend myself. The threat is when he/she gets out of the car after trying run you over, no telling what might come out of their pants/car.
Cars dont turn on dimes, so it's possible to fake the driver, shoot for the tries. If you shoot at them in the windshield once or twice they will duck and not beable to see the road, this is your chance to make a dash.
I would be more worried about moving out of the way, even if you HIT the driver he/she is still in a 2000lb+ moving car thats rolling at you. So moving out of the way is most important.
SHTF vs TEOTWAWKI you ask? SHTF, just some crap on the ceiling and walls, TEOTWAWKI end of the world as we know it. Orignally made by 9mm/®™©