We don’t need to tell you that the Lamborghini Aventador SVJ is quick. It would still look like a fast car even if it were powered by a lawnmower engine. But at the other end of the spectrum, there’s a whole group of cars that conceal powerful drivetrains beneath the metal of a normal car. So let’s take a look at some of the best ‘sleepers’ ever sold and check up on how easy they are to buy today.