Audi and Lamborghini are two distinct branches of the Volkswagen family tree, but they bear some similar fruit in the form of a shared V-10 engine. The V-10 in question derives from the Lamborghini Gallardo. Although the Italian version generates 560 hp, it’s tuned for only 435 hp in the Audi S6, which puts the car at a disadvantage against the BMW M5’s 500-hp V-10 and the Mercedes-Benz E63 AMG’s 525-hp V-8 monster. Those looking for something nice?not naughty?should turn to their attention to the Audi A6. From the outside, revisions to the new A6 appear to be relatively minor: The refreshed grille, bumpers, air vents, fog lights, and optional LEDs round out the list of styling modifications. Press the throttle, however, and the new 3-liter supercharged V-6 engine—dubbed 3.0T by the German automaker—is almost impossible to ignore. With 300 hp and 310 ft-lbs of torque, the Audi A6 3.0T provides a smooth ride to 60 mph in less than 6 seconds and boasts the added benefit of better fuel mileage—up to 26 mpg on the highway. Pros: Now that the S8 is retired, the S6 is the only sedan on the market with a Lamborghini-sourced engine. Cons: A little long in the tooth.