Quick loud speaker/PA system
I have an awesome idea take one of those small FM transmitters and combine it with a laptop you could park cars close together and turn up the stereos and have an instant Loudspeaker and drown out protesters. The amp on the laptop with the right kind of volume adjustment would make a clear loud signal, just make sure the vehicle broadcasting has sound dampening to prevent feed back. I was experimenting today with my transmitter and figured it out.