However I would love to get a directed EMP device for my car, so if "Thumpy" is next to me in traffic sharing his music with everyone I can kill every bit of electronics in his car.""
I would buy one of those devices.
This is America- can anyone out there make such a device and make it very specific? Perhaps tie the directionality of the "pointer" with the high volume of the offending car/driver? Then you wouldn't spread your inpulse and stop all traffic on the spot.
"This is America- can anyone out there make such a device and make it very specific? "
Nope. It won't work. Producing an EMP large enough to take out a car stereo system would require enough equipment to fill a semi trailer.
In the first place, the stereo system is pretty well shielded by the metal car body. In the second, the systems are generally designed to handle at least 1KW of power sent through the system. A directed electromagnetic beam would have to be powered by a huge power system to affect such an audio system.
It ain't happening.
However, if you can get into the trunk of one of these boomer cars, a simple shunt to short out the woofers (use large diameter wire) will destroy the woofer's amplifier or, at least, blow its fuses. However, I do not advise messing with some banger's vehicle.