I say this as someone who has banged on a car and then been chased by the occupants: It’s not worth it. Even if, as is usually the case, the driver is the one at fault in a driver-runner contretemps, let it go. You’re not going to change the driver’s mind about the situation, you’re allowing the driver’s irrationality to have too much of an effect on your run and you really don’t want to find out that you’ve pushed some nutcase over the edge while he’s operating a two-ton vehicle. If you must have some satisfaction from the encounter, kill him with kindness—when he honks and shakes his fist, smile and wave.
Similarly, it’s not worth it to respond to the too many people (usually male teens) who are entertained by shouting supposed insults at passing runners. Even more so than with a potentially distracted driver, you’re dealing here with people acting irrationally. (If they were being rational, why would their supreme intended insult be to yell, “Faggot!” As if sexual orientation has any connection to the fact that you’re running down the street.) Returning their taunt is just giving them the attention they want.