Thats the key.
I get out and shout, he gets out with a knife.
I get out with a bat, he gets out with a gun.
Maybe a tad extreme but when you live in a major city, these things can't be 100% ruled out. You never know what the next person is capable of. Not worth getting involved with, stay in your car and then when the road clears, drop the window and give them the bird *
* And then hope there are no traffic lights ahead