I commute every day through DC as well and have come across my fair share of a-holes as well. If you are still really steamed after a while then maybe you need to do something about it, just let it simmer a little while before you do something stupid.
I don't condone smashing up someones car (I am a car nut) but it wouldn't hurt too much to inconvenience him by, say, slashing his tires
Just don't smash mirrors, or bash his door in.
Informing the police of his license status would be real harsh. If you feel that strongly about it that would probably be the best way to mess him up. But that is opening up another can of worms that is probably best left closed.