There might have been a stray incident or two but usually bikers stay on the lanes which are for slow driving. They are concerned about their own safety. Surely, no biker would like to get knocked off by a car whizzing past at 100kph. I know of a young man who drives a 250cc motorbike. If he overtakes your BMW and shouts mockingly at you saying, "Catch me if you can", just overlook him!