To categorise is difficult, but here are 2 types I often meet:
Idiots without the imagination to visualise what maimed and dead bodies look like in a car crash - so theyd rive like dicks. They usually also have rage problems and can drive aggressively.
There are also distracted, elderly etc. who make silly mistakes. They can still kill you.
I reckon that whereas 20 years ago I would get cut up maybe once or twice on a long journey, it's now every few miles - millions more cars, same percentage of bad drivers.
And it's no longer hothead male teenagers in a Saxo - most of them seem to be crazy women in company cars or 4x4s.
IMHO rage is a natural response to being nearly killed. Fear may come before you face a danger, but rage is there to help you once attacked.
Now I'm not saying this will work for you, but it does for me, as I lack a Hummer or DH's tank to crush the buggers:
Start your journey with the strong wish not to get annoyed and set yourself a target of, say, 15 minutes. Give way to anyone who wants to push and just pity the poor sod who may be close to losing his job if he missesd the appointment, may be late to pick up a child etc etc. If you smile at them, smile - don't laugh as this pisses them off as much as the finger (for which you can also be arrested in the UK, I believe, as it is 'threatening behaviour likely to cause a breach of the peace' or some such tosh). At the end of the journey you will be amazed how much better you feel.
Alternatively, buy an ancient Jeep or Land Rover. Weld angle iron all round it - and when they push, stay put. Don't push back, don't play chicken, just don't be the one forced out of the way. Worked a treat for a 92 year-old granny near me! She must have scarred dozens of dickheads. (When driving, I mean...)
FFF, aside from the tank, is dead right - you get out and even here in the UK if you are dealing with an angry young male, it often comes with a knife or lump of wood, and/or his mates. Or in Bristol or Nottingham, a pistol. Not worth it.
One mate of mine is a bouncer with a really bad temper. Came to the gym the other day and told me some guy had been screaming in his face about blocking his driveway with bad parking. Apparently, he just said he was really really sorry, had no idea etc. as he was just so fed up of the usual trouble his temper got him in. Good move.
Only one really bad move I would add to the list - never open the car window and give the guy the chance to introduce his fist to your face while you are trapped.
I've seen dead children and adults and everything in between in road crashes and man, does it make you think about safety. Addding road rage to the mix is never worth it.
Good stuff all, I appreciate all these responses.
Don Gwin: You might be right. I am normally the calmest, most even tempered individual. I am that guy that breaks up the fights, not instigating them. This guy, with the hummer, the license plate, and absolute lack of concern for fellow drivers just pressed all my buttons. Learn something new every day I guess.