The multiple displacement system (MDS) was created by chrysler to improve the fuel economy of its 5.7L V8. The idea was, when the engine wasn't being run hard, it would turn off half its cylinders, thus improving gas mileage while keeping it's sportiness. This, of course, made it seem like a no-brainer for many police departments, so when they bought Interceptors, they took the option. Unfortunately, turning off half the cylinders affected the engine's counter weights and balance, so whenever it kicked in the engine would rattle, roughly enough so that if it happened to your car, you would take it to the mechanic. Much of a patrol policemen's day is in his car, so that would hardly be enjoyable. It would also kick in when the car was in park, such as a cop doing a speed trap would, making it a very angrily idling car. All this discomfort (and wear to the engine), for a economy increase of about 2 miles an hour. In addition, the economy is improved suing a different piece of tech, the transmission. To get the transmission in a cop charger to downshift you have to really step on it, and that, if nothing else, saves gas. For those of you in the market for a car with this system, police or otherwise, let me tell you, its probably not worth it.