The Audi RS 6 Quattro, or just RS 6, is the highest trim level and highest-performing model under the A6 heading for the German car maker. The RS 6 was produced as both a wagon, or Avant, and a sedan. In both forms it has been praised for its good looks and excellent performance elements. Not many versions of the RS 6 made it across the ocean to the U.S., which means that this is a modern classic. Find your next Audi RS 6 purchase here at FossilCars. We offer the best and most extensive listings for classic and soon-to-be classic cars.