During the World Wars, Allied navies equipped seemingly harmless merchant ships with guns and torpedoes to ward off prowling German U-Boats. Called Q-Ships, they were all about the element of surprise. The best sleeper cars are automotive Q-Ships.
There’s no rule that says a performance car has to have two doors or the low-slung body of a sports car. Disguised as sensible sedans and wagons, sleepers keep a lower profile. Sleepers are cars for serious performance junkies — without the flash of traditional performance cars, they can’t be used to show off, and they put automotive performance in practical packages. They also provide the satisfaction that no one else has any idea what kind of fury lies under the hood.