I am like yourself. I will and have banged on a car, truck and van more than once in my years of cycling. There are other posters here that manage to place themselves in a zen like trance whilst cycling that helps them ignore the idiots in cars around them. I am sure it will make their injuries and or fatalities much less tramatising should, god forbid, some white van man runs them over.
Case in point as it happened to me:
Cycling to work I met a funeral processing of several vehicles. I pulled to the side of the road behind a parked car, stopped and removed my helmet (yes, gasp!, I wear a helmet) to pay my respects. A large, flatbed builder truck was following. As the last of the procession went by I started to put my helmet back on. Next thing I know the truck is trying to park in the spot I am sitting. I dropped my helmet and grabbed the side board of the truck shaking it with my two hands and started shouting at the driver to stop, his double back wheels inches from me he stopped. He yelled "Get the F out of the way!", jumped out of his truck and started for me. I pointed to my camera and told him he was being recorded. He turned on his heel, got back in his truck and pulled off again almost running me over. I showed my wife the video when I got home and she cried because of the unprovoked attack on myself by a yob in a truck.
My bloody mirror did not help and the fact I had a camera only prevented a physical confrontation because I dared to vebally protect myself. He certainly did not see I had a camera until I pointed it out. I did absolutely nothing to provoke this vehicular assault on myself. I certainly would have liked to have video recorded some of the afore said posters reacting to the same situation.
As far as stiking a vehicle that is too close, there is highway code 163 that so many drivers ingnore. I, like my zen embracing fellow riders, tend to not react to most that pass by too close. But when one is so close that I can hit it and I have no place to go or to stop, bang on I shall. Stay tuned to youtube.........................