Here's a true story.
In 1970s israel, color TV broadcasting finally arrived, since the world switched to "living color" broadcasting. The israeli government feared the social effect: until then, both rich and poor had B&W TV; what would happen if the rich will now start buying color TVs while the poor would be stuck with the B&W ones? So they hit on a wonderful device known as the "mehikon" ("eraser"). This gadget "erased" the color from all israeli TV broadcasts, by "translating" all color into various shades of gray. This meant that even if you had a color TV, and the original program broadcast was in color, you'd recieve it in FAKE B&W! (think of the "coloring" of old pictures, only in reverse).
Needless to say, within a few weeks a new gadget arrived: the "anti-mehikon", which you could attach to your color TV, and translate the gray-scale color images back to their original color, so you would get a color broadcast after all. So the evil rich people got a color TV with an anti-mehikon, which made the mehikon the laughingstock of the entire country. It was soon discontinued.
Same thing here. The sole result of this thing would be that those who could afford to will buy a "anti-stopping" gadget that would defeat the cop's device and not allow the car to be stopped. In effect, the only people who it will really stop would be the poor schmucks who could not afford to buy the gadget.
As an aside, I think a similar VOLUNTARY system like this does exist with many car-theft-protection services: you can AGREE with them to install a gadget in the car that stops it when it goes beyound a certain speed, as an anti-theft device, when you know you never drive so fast and if somebody does, it means the car was stolen. It is not the idea itself that is wrong--it's making it compulsory.
By the way, wouldn't "killing" the engine at 90 MPH be a sure way to create TONS of accidents?
