Like most Audi models currently on the market, the S6 looks like a comfortable luxury sedan to casual observers—until they hear the throaty baritone of its twin-turbo 8-cylinder engine. Based on the stylish and powerful A6, the S6 improves performance and adds luxurious extras. The S6 got a minor facelift for the 2016 model year and goes into 2018 without significant changes.

The main reason to step up to an Audi S car is performance: under the hood of the S6 is the familiar 4.0-liter twin-turbo 8-cylinder that is rated at 450 horsepower and 406 pound-feet of torque. In the S6, this engine is mated to a 7-speed dual-clutch automatic transmission and features Quattro all-wheel drive (AWD). Despite its heft, this big sedan will scoot from 0-60 mph in 4.4 seconds and reaches an electronically limited top speed of 155 mph. Sipping premium fuel, the S6 will return 16 mpg city, 24 highway, and 18 combined.

Audi’s Quattro AWD system splits power 60/40 rear to front in the S6, and the steering is by electronic power assist. Suspension features the automaker’s adaptive air suspension, and drivers can choose between Comfort, Auto, Dynamic or configurable Individual driving modes. An available Dynamic Steering package adds a variable ratio assist to the steering and is bundled with a sports exhaust, red painted brake calipers, and a sport rear differential. A bit big for track days, the S6 is most in its element during highway cruising and high-speed passing, but it is more than competent cornering as well.

With contrast stitching, carbon fiber accents, and interesting color choices for the upholstery, the S6 interior is more distinctive than its understated exterior styling. A shorter than the S8, the S6 has a fair amount of room, including comfortable seating for five and 14.1 cubic feet of space in the trunk. Standard features include a Bose stereo, sport seats up front, a navigation system, Bluetooth compatibility and Audi’s Multi Media Interface (MMI) infotainment system. Optional extras include a cold weather package, night vision camera, massaging front seats, and an Alcantara headliner.

Expensive cars like the S6 don’t go through the usual crash tests. However, standard safety features include a reversing camera, and an available Driver Assistance package comes with adaptive cruise control, Audi Pre Sense Plus system that tightens seatbelts when it detects an imminent collision, and active lane control. The S6 is an expensive car, but it rewards buyers with effortless acceleration, a brilliantly executed premium interior, and cutting-edge technology in both the convenience and safety fields.