Just reading this thread absolutely infuriates me! God, I am afraid to think what I would do in such a situation. I am a super mellow guy, but if something like this happened to me, I would simply becomed enraged.
Then I would take off after the F*$%'ers in an anger-induced, Sith-like rage, hoping against hope to catch up to them so that I could punch my bike-glove-covered hand right through their driverside window.
Then they would jump out of the car, beat the crap out of me, and I would probably get arrested.
Of course, this whole scenario is exactly why I will never return to america.