I have punched hoods, but only when (a) I felt the driver was ridiculously negligent (not aggressive or belligerent, because those are the MFers who will attack, and in PHX they're likely to be 2nd Amendment supporters) and (b) when there was a clear escape route for me. Usually the driver looks all put-upon, like "Why would you smack my poor widdle car?" This pisses me off even more, so I try to avoid these altercations. De-escalation is the key.