1. Audi RS6
- Years: 2008-2010
- Sure, it’s an Audi sedan, and while some RS badging and bodywork is a dead giveaway to the cognoscenti, the layman walking past the second-generation Audi RS6 in a parking lot would have no idea that underneath the hood lurks a 570 hp V10 originally designed for the Lamborghini Gallardo.
- Years: 1989-1999
- Close your eyes and picture a sedan with a high revving Yamaha motorcycle engine and a bunch of other go-fast bits. Then open them and take a second look at the Taurus SHO, a car which many consider the ultimate sleeper car. Just as amazing, the third generation SHO had a V8 under the hood built as a collaborative effort between Yamaha and the legend that is Cosworth.