I am loathe to admit that this has happened to me too. The worst part is that I have always failed to get a plate number. In the recent past, I have been making a game of noting make, model, and number of vehicles as they pass me and for some reason this type of behavior does not happen any more. It may be that I simply look more alert to the morons.
The most interesting one was a case of a SUV with a bunch of girls in it. (This is a motorcycle story, sorry) I was on I5, which is a four lane (two in each direction) highway that runs the length of California, and happened to notice, in my mirror, a white SUV (it was a Chevy Tahoe, I remember that because that is what I drove at the department I was at, at that time) coming up behind me and driving erratically. I also noticed the cars being passed driving erratically. It was as she pulled onto the inner shoulder in order to pass the car next to me that I saw the reason. As they passed vehicles they were throwing coins and I observed one windshield, on the car in front and to the left of me (as I was in the #2 lane) damaged. I then rolled on the throttle (sounds cooler than “increased my speed”) in order to approach, only, near enough to copy the plate number.
I suppose at this point I must describe my bike, It is a grey and white Yamaha V-Star 650. It has spot lights (two lights next to the head light) a Q-beam (the motorcycle headlights that can be caused to change in intensity) a tall windshield and two large, white, side cases. Yes, I know what it looked like and I can say with confidence that I have had fewer close calls on that bike than any other that I have had.
I split a few lanes to approach and she clearly saw me. She greatly increased speed and the passengers stopped throwing coins. I was not willing to initiate any sort of a chase (I was on my own time). The next I saw her was on an off ramp that was about three miles down the road. I began to use the off ramp in order to confirm that it was the same vehicle, get the plate number, which I had failed to do previously, and to place a phone call to CHP from a nearby truck stop. The driver observed my presence and immediately left at high speed into a series of side streets.
I still made my phone call and described the vehicle. I suspect that she, and her passengers, were done throwing coins for the day.