"I've never figured out what they are good for." Use your imagination a little -- they make great mobile guillotines. Come the revolution... .
Just joking, Dick, Rummy, just joking. Hm. Shouldn't be giving these guys ideas, should I?
Much better is to have front-seat passenger stand, armed with assault rifle or light machine gun resting on metal part of roof, fully loaded and at the ready to take out discourteous drivers with tracer bullets to the fuel tank;-)

We really have to do something about road rage.