s,
I'm sorry that I don't have a solution for you to the question you posted. I only offer one small bit of advice, which I recognize might not have helped in this specific situation:
Anytime you come to red light, stop sign, or other situation where you have to come to a complete stop, and there are cars in front of you, don't park on the bumper of the guy in front of you. Leave a good 3-4 feet between you.
That way if you have to scoot, you have enough room to make the turn and or accelerate. Yes it might be up and over the center island or the sidewalk, but if someone's coming up to the car or already shooting, any edge might help escaping.
Good rule of thumb is that you should be able to see the rear tires of the car in front of you.
You do really have to be aware of the laws of your state regarding self-defense if you're going to make the decision to carry a firearm, and that way you'll be able to gear your thinking and training in that direction. If you think your laws regarding self-defense are unreasonable, get involved with a pro-2A group in-state and start to do something about it. Glad everything turned out OK, but use this as an opportunity to educate yourself, and others.