motorcycle
Jumping out of the way is probably the right way to go, but don't expect it to be really easy or clean. I did face this type of situation when I was 18.Not with a gun and not a car.
I was crossing the street to get to a bus that was going to take our group to a restaurant. Suddenly this large motorcycle (Honda 650 as it turned out) piloted by a drunk (determined by police at the scene) came screaming around the corner. I saw him coming and ran like hell for the other side of the road. His reactions were a bit slow, so he turned where he thought I wasn't going - and instead turned and headed right for me. I saw I wasn't going to make it in that direction, so I spun around and headed the other way - for three steps. In the meantime, this dimwit's brain told him to turn the other way too - a second too late - and I saw that there was no way to avoid him. I jumped, almost made it, my left leg got clipped while I was in mid air, I flew about 10 feet and he wobbled to a stop about 50 yards further. My left leg was broken in two places, my back was sprained, and my shoulder and chest were badly bruised. I ended up spending over a week in the hospital (this was 40 years ago, so it was less unusual than now).
Lesson 1: This happened in less time than it took you to read this. All thoughts were in impressions rather than words.
Lesson 2: If I had jumped a second sooner, I would have avoided being hit, a second later and I would have been seriously injured or dead.
Lesson 3: I couldn't care less what you think you would do, it's all different when that screaming hunk of steel is right there.
Lesson 4: It changes your life. The ensuing post-trauma arthritis put an end to almost all of my sports - no more tennis, no more skiing, no more running; it's not fun when every step makes your ankle crack and sends shooting pains up your leg. Of course that also translates to pain on walking up hills, stairs, long distances on the flat. I've gutted it out for 40 years with only NSAIDs to keep things in check.
Lesson 5: Don't be an idiot, get out of the way as best you can, if you shoot the guy and just get clipped by the car, you'll still likely be paying for the incident for the rest of your life - and I don't mean court costs (see lesson 4).