As much as it pains me to say so, it is nearly always better to back off in these situations. Put your brakes on and let the car past, try to pull out of the way, anything to avoid potential contact with the car.
As for remonstrating with the driver, again my approach is to avoid it.
I realise that we should not have to do this, but unfortunately, as we know, there are quite a few maniacs out there and their numbers are growing. The chances are, you will come across one of them someday and you simply don't know what they are going to arm themselves with. If they arm themselves with a foul mouth or fists you might be able to get the better of them. If they arm with a wheel brace, iron bar or knife, you are going to look a bit second hand by the time they have finished with you and in my view it isn't worth the risk.
It takes a lot of effort for me to resist saying or doing something if a car driver puts me in danger, but the annoyance factor soon subsides and by the time I arrive home, in one piece, I have usually forgotten all about it.
As for that worthless bullying lump of lard driving the BMW. If he is caught, he needs hurting and hurting badly. People like him only understand pain and violence. He needs to experience a violent episode that will mentally scare him for the rest of his life. Only then will he think about the effect of his actions on innocent and undeserving people. Not a very attractive solution, but I'm afraid that's where we are.