4 on 1, I would have chickened out on starting a fight. I would have done the next best thing, and followed their sorry asses. Then, if they didn't head home so I could tell the little bastard ass's Mommy what her kid did to my car, I'd call the cops. Report the little pricks, and let them deal with it.
Or, I would have waited until the perfect opportunity, and threw ANYTHING I had in my car through their window, and sped the hell off.

Channel locks, full cup of Pepsi, a sharp pen... Anything that can do some damage.
Mark