The rental car issue was indeed a big problem. If I remember correctly a couple of German tourists were killed during one of these bumper tag episodes. At the time all of the rental cars had a sticker in the back window with their logo so you knew that it was a rental car, it made it very handy for the bad guys to identify the non-locals. I believe they actually passed a law that said there could be no identifying marks on the exterior of rentals after that.
I remember this.