It has taken some time for me to find ways of dealing with these sorts of things (or people, or events). One way that seems to help is to make those repeated kissing sounds -- the sorts of sounds some people use when calling a pet cat.

(This technique also seems to lighten things up when being barked at (by a dog)(which is actually rather similar to being barked at by a human).)

At times, it is better to make the sounds in your mind, rather than out loud -- especially if it is a real road rager who is already well on the way to losing control.

***
Another way that has worked for me is to say something like 'What an idiot', either out loud or (usually better) to oneself.

I have to say, though, that I am not entirely at home with this. Maybe it's a perfectly intelligent (okay, somewhat imperfectly intelligent) person, who is just doing something a little out of character -- maybe the person is in a bad mood, or is having a bad day, or was just upset by a fight with his wife or boss or coworker or son or father or girlfriend, or just got (or thought about) some bad news, or is just having a hard time in life....

It helps a lot sometimes to be very charitable.

***
A lot of the misery I have experienced (at times, in the past) after these sorts of incidents can be traced to my own reaction (of dislike for the person). If I keep clear of those sorts of reactions in myself -- if I (genuinely) do not get angry or hateful -- somehow my inner (emotional) environment, and my own thoughts, do not make me miserable....

It is somehow lighter inside.

That seems like the best way I have found -- not losing the sense of lightness and cheer and good will for all.

There is a kind of gentle and natural protection that goes with keeping the good will alive and going.

***
Sometimes I just say, 'I hope he comes out of it' or, 'Probably he will become a more loving person at some point' (--and I think this is true: he will ... it may take some kind of learning; it may be quick, or it may be long; but eventually we all come around to being larger, more mature and loving persons).