The S6 is a high-performance version of Audi's A6 sedan, which is covered separately in the Research section. While the A6 employs V-6 or V-8 power, the S6 has a 435-horsepower V-10. Both cars were lightly restyled for 2009. Competitors include the BMW 5 Series, Mercedes-Benz E-Class and Infiniti M.
The S6 packs a standard six-speed automatic transmission and Quattro all-wheel drive. The S6 comes only in one trim level, Prestige.
The S6 looks the part of a gussied-up A6, with bumper-mounted LED lights in place of the A6's lower fog lights. Unique front and rear bumpers and aluminum trim on door- and windowsills complete the package.
The most distinct visual changes between 2008 and 2009 versions of the A6/S6 are in back. The trunk gets new chrome accents, and the taillights drop the '08 model's squared-off design for something closer to the new A4's: They're wider and carry around to the trunklid.
The S6 comes standard with 19-inch wheels.
Besides unique leather seats with S-line logos and thicker side bolsters, the S6's wraparound cockpit sees few changes from the A6's. The S6 does come loaded, though, with standard heated leather upholstery, power front seats, a moonroof and a navigation system; a Bose stereo with a six-CD changer and full iPod/USB compatibility also are standard.
Audi's Multi-Media Interface places a control knob with a few shortcut buttons around it ahead of the center console. Like BMW's iDrive and Mercedes-Benz's Comand, MMI governs various navigation and stereo functions through a central dashboard display. A third-generation MMI system is in store for the 2010 A6/S6, with improved graphics and better usability.
The short list of options includes heated rear seats and carbon fiber interior trim.
Under the Hood
The S6 is stoked by Audi's first-ever V-10 engine, a normally aspirated (not turbocharged, not supercharged) 5.2-liter with direct injection. It combines the generous torque characteristics of a high cylinder count with the high-rev output of a 7,000-rpm redline, delivering 398 pounds-feet of torque at 3,000-4,000 rpm (with 90 percent on tap at 2,300 rpm) and 435 hp at 6,800 rpm. Audi cites a zero-to-60-mph time of 5.1 seconds, a quarter-mile time of 13.4 seconds and a top speed electronically limited to 155 mph.
The S6's Quattro all-wheel-drive system sends 60 percent of the torque to the rear wheels as a default, and up to 85 percent when called upon. The previous generation of Quattro for both cars split the torque 50/50, front/rear. The change gives the Audis equipped with the new Quattro dynamics closer to those of a rear-wheel-drive car.
Both the A6 and S6 are rated Top Safety Picks by the Insurance Institute for Highway Safety, thanks to their top performance in frontal-, side- and rear-impact crashes.
In addition to the required frontal airbags, the S6 includes seat-mounted side-impact airbags for the front passengers, and side curtain bags that deploy along the front and rear side windows. Antilock brakes, traction control and an electronic stability system are also standard. Seat-mounted side-impact airbags for the backseat are optional, as is a blind spot warning system.