The A6 lineup includes models with turbocharged 4-cylinder (2.0T), supercharged V6 (3.0T) power, and a direct-injected turbodiesel V6 (3.0 TDI). A6 2.0T models are offered with either front-wheel drive or quattro all-wheel drive, while 3.0T models all include quattro. 2.0L turbocharged models generate 220 horsepower, while 3.0L-powered models manage 310 horsepower and 325 pound-feet of torque. The 3.0 TDI, meanwhile, delivers 240 horsepower and an impressive 428 ft-lb of torque. Base models of the A6 with front-wheel drive (labeled FrontTrack) include a continuously variable transaxle (CVT), but the rest of the lineup utilizes an excellent 8-speed Tiptronic automatic. On any of these models, a rear-biased version of Audi's quattro system sends 60 percent of torque to the rear wheels under normal driving, giving it more balanced handling, while the A6's construction uses a combination of aluminum panels and high-strength steel to save weight and improve the A6's nimble, responsive feel. Thanks to Audi Drive Select, steering and throttle are adjustable, as is transmission behavior. Inside, the A6 is beautifully detailed, with a wraparound design, supportive seats and just the right amount of bright trim. Inside in most models there's 3- or 4-zone automatic climate control and ventilated seats are available. In addition, there are some standout technology features, such as built-in WiFi connection, Google Earth maps for the navigation system and integrated Google Local Search. The A6 is also strong on safety features, with a Pre Sense system, which initiates protective measures if it anticipates a collision, included in all A6 models. There's also available adaptive cruise control and an Audi side assist option that warns of vehicles potentially in the driver's blind spot. Those willing to splurge on options are also able to get a night-vision assistant and head-up display, as well as the phenomenal 1,300-watt, 15-speaker Bang & Olufsen Advanced Sound System. A 630-watt, 14-speaker Bose surround sound system is also available. Key trim levels for the A6 2.0T are Premium and Premium Plus, while the 3.0T and TDI start at Premium Plus and are also offered in a Prestige trim. Premium Plus models add keyless start, LED running lamps, a parking-sensor system and Audi's MMI Touch screen-driven interface with HD Radio, plus navigation with SiriusXM traffic. The top Prestige model steps up to 4-zone climate control, the Bose surround system, heated-and-ventilated front seats, a power-adjustable steering column, LED headlamps, LED ambient lighting, Audi side assist with Pre Sense, plus appearance extras. The S6 is a high-performance variation on the A6 but a big step up in performance, thanks to its 420-horsepower, 4.0L turbocharged V8 engine, along with a special 7-speed S tronic gearbox and various other performance upgrades. The S6 has a stiffer performance suspension, as well as an air suspension system with variable damping and four modes. The S6 supports its performance credibility with upgraded ventilated disc brakes with matte-black calipers, a 4-outlet dual exhaust and special 19-inch cast-aluminum wheels. A "cylinder on demand" system can temporarily shut some cylinders off to save fuel, while active engine mounts and active noise cancellation keep the vibration at bay. Inside, the S6 gets special power-adjustable S6 sport seats, Valcona leather seats with diamond stitching, leather steering-wheel trim with colored stitching, illuminated door sills and special sport seats.