It is possible now to hack a car. Not eminently practical, but give it a few years. I can see a time, real soon now, when anyone with a transmitter will be able to transfer malicious code to nearby vehicles, completely undetected.
One with a modest amount of power would be perfect for those annoying tailgaters, and could bring a stop to their practices before they get to the stage of turning on those red and blue flashers. It could even turn off those flashers, and all the other lights as well.
I want one.