JamesAC said:
Well, we can slink away with our tails between our legs and pretend it didn't happen.
Look at it that way if you want.
If they get out of the car, you're f*cked. Whatever Bruce Lee does in the films, you don't have much of a chance against more than one person, because they (in general) aren't going to wait their turn at hitting you.
If they stay in the car, you're f*cked, because cars are big and heavy and go really fast.
Escalate things if you feel you need to, for whatever reason, but do be realistic. You're not holding a strong set of cards in most bike/car situations, unless you're riding with a few other people who like to mix it as much as you do, and the objects of your retaliation choose to leave their car to sort things out like gentlemen.