If you like your luxury served with an extra helping of performance, the 2016 Audi S6 could be just the sedan to satisfy your craving. A muscled-up version of the well-regarded A6, the 2016 S6 is the rare midsize luxury sedan that manages to be stylish, comfortable and thrilling all at once.

The 2016 Audi S6 cuts a dashing figure without going over the top.

As expected of an upper-class Audi, the S6 pampers you in its handsome cabin, which boasts rich materials, exemplary fit and finish and a long list of high-tech features. The nicely contoured sport seats will soothe you on long road trips just as easily as they'll keep you planted on a back-road sprint. Less expected is the jaw-dropping acceleration provided by the standard twin-turbocharged 4.0-liter V8. Rated at 450 horsepower -- 30 more than last year -- this engineering masterpiece is as refined as it is capable, joining forces with the sport-tuned adaptive air suspension to deliver stunning athleticism in spirited driving.

The big news for 2016 is the MMI infotainment system's overhaul. We were already impressed by the S6's cabin technology, but this year's revisions take it to a new level. Thankfully, Audi has ditched its proprietary music interface in favor of dual USB ports, facilitating both connectivity and charging for a wide range of phones and music players. Other MMI enhancements include Siri Eyes Free (voice controls for Apple devices), Internet radio integration and a quicker graphics processor.

As midsize luxury sport sedans go, the S6 competes mainly against the V8-powered BMW 550i. With its new power boost, however, the Audi now edges the 445-hp BMW in output, and it's nimbler on twisty tarmac. The 2016 Mercedes-Benz E400 sedan is another option. It's priced a little below the S6 and offers a superb ride in exchange for a bit less performance. You could also check out the redesigned 2016 Jaguar XF or the Cadillac CTS Vsport, which is a 420-hp bargain. They're all compelling alternatives, to be sure. But the 2016 Audi S6 continues to stand out as an exceptionally well-rounded player in this competitive league.

The 2016 Audi S6 is a high-performance version of the A6 midsize luxury sedan. It's offered in two trim levels: Premium Plus and Prestige.

Standard exterior features for the Premium Plus trim include 19-inch wheels with summer tires, S-specific styling elements, automatic xenon headlights, LED running lights and taillights, a sport-tuned adaptive air suspension, a sunroof, heated auto-dimming power-folding side mirrors, front and rear parking sensors, a blind-spot warning system and keyless ignition and entry.

Inside you'll find a driver information center with a 7-inch display between the gauges, Audi's Drive Select (providing adjustable settings for the steering, suspension and transmission), diamond-stitched leather upholstery, heated eight-way power front sport seats (with four-way driver power lumbar), a power-adjustable flat-bottomed steering wheel, driver memory settings, four-zone automatic climate control, an auto-dimming rearview mirror and 60/40-split folding rear seatbacks.

Electronics highlights start with the MMI infotainment system, which includes a console-mounted control knob with a touchpad that can read your fingertip scribbles, a central 8-inch display, a navigation system with Google Earth maps, voice controls (including Siri Eyes Free for iOS devices) and Audi Connect (including enhanced Web-based information services, 4G LTE data connectivity and mobile WiFi capability). Also standard are a rearview camera, Bluetooth phone and audio and a 10-speaker sound system with a CD player, two USB ports, two SD card slots, HD Radio, satellite radio and streaming Internet radio.

The Prestige trim adds LED headlights, a power trunk lid, a 14-speaker Bose audio system, a head-up display, LED interior lighting and rear sunshades (manual for the side windows, powered for the rear window).

The LED headlights, Bose audio system and rear sunshades can also be added as options to the Premium Plus. Exclusive options for the Prestige trim include a night-vision system and a 15-speaker Bang & Olufsen sound system.

Most other options, available for either trim, are organized into packages. The Driver Assistance package adds adaptive cruise control (with stop-and-go functionality), lane-keeping assist, a surround-view parking camera system, a forward collision mitigation system with automatic braking and automatic high beams. The Comfort Seating package features multicontour front seats with ventilation and massage functions, front passenger memory settings, comfort rear seats and leather upholstery (sans diamond stitching). The S6 Sport package provides dynamic steering, a torque-vectoring sport differential and a sport exhaust. The Cold Weather package adds heated rear seats and a heated steering wheel. The Black Optic package tacks on exclusive 20-inch wheels, body-color exterior mirrors (instead of the standard silver ones) and gloss-black exterior trim.

Stand-alone options include 20-inch wheels and rear side airbags.

The S6 is powered by a turbocharged 4.0-liter V8 that pumps out 450 hp and 406 pound-feet of torque. The transmission is a seven-speed automated manual called "S tronic" that works in concert with the standard all-wheel-drive system.

This is the view most rivals will have of the 2016 S6. It's one of the quickest midsize sport sedans we've tested.

In Edmunds track testing, the S6 scorched the pavement, needing just 4.1 seconds to accelerate from zero to 60 mph. That's serious speed.

Remarkably, fuel economy is also a strength, as the S6 earns above-average EPA fuel economy ratings of 21 mpg combined (18 city/27 highway).

Standard safety equipment on the 2016 Audi S6 includes antilock disc brakes, stability and traction control, front-seat side and knee airbags, full-length side curtain airbags, a blind-spot warning system, forward-collision mitigation, a rearview camera and front and rear parking sensors.

Rear side airbags and a night-vision system are optional, as is a sophisticated Driver Assistance package that includes an active lane-departure warning/keeping system, adaptive cruise control and the Audi Pre-Sense Plus collision mitigation system, which warns the driver and can automatically activate the brakes and adjust the front seats for maximum protection if a crash is deemed imminent.

In Edmunds brake testing, an S6 with 20-inch wheels and summer tires needed 111 feet to stop from 60 mph, a few feet longer than we expect of a car in this class.

In government crash tests, the Audi S6 received five out of five stars overall, with five stars for frontal crash protection and five stars for side crash protection. The independent Insurance Institute for Highway Safety gave the similar 2016 A6 its highest rating of "Good" in all of its safety tests, including the moderate and small-overlap frontal crash tests, the side-impact crash test and the roof-strength test. The A6's seat and head restraint design was also rated "Good" for whiplash protection in rear impacts.

The S6's 450 horses technically pit it against conventional sedans like the 445-hp BMW 550i. However, its astoundingly quick acceleration in our testing shows that it's also an able substitute for German tuner sedans like the 560-hp BMW M5 and 577-hp Mercedes-Benz E63 AMG S -- for potentially tens of thousands less. Moreover, the engine's refinement is about as good as it gets, and the same goes for the automated manual transmission, which is equally content ripping off perfect rev-matched downshifts or just trundling around town.

On the handling front, the S6 approaches sports-car territory with its quick steering and tenacious grip, yet the standard air suspension keeps the ride civilized on all surfaces. There are cars that do certain things better than the S6, but very few can match this Audi's all-around excellence.

It only takes a few moments inside the 2016 Audi S6 to realize that this is one of the nicest cabins on the planet. Highlights include a handsome dashboard layout, top-quality materials and excellent fit and finish. The standard MMI infotainment system integrates the car's entertainment, communication and navigation functions, which are controlled through a dash-mounted pop-up screen and an easy-to-reach knob-and-buttons layout on the center console. The system boasts logical menus, crisp graphics and a touchpad that lets you use finger movements to spell out addresses, search your contacts list and perform swipe commands, among other tasks.

The 2016 S6's interior is one of the most well-crafted you'll find. Its high-quality materials are matched by an array of advanced features.

The S6 also features Audi Connect online services, including an in-car WiFi hotspot with 4G LTE connectivity, Google Earth data for the navigation system and simplified Google search functionality for points of interest. The mobile WiFi allows passengers to access Web content on their mobile devices, and it proves very handy if you need to get work done on the road with no Starbucks in sight. The Google Earth feature is a mixed bag, however, as it's a bit harder to understand at a glance than a conventional map display.

Whether you keep the standard sport seats or opt for the multicontour comfort seats, you'll enjoy excellent support during both long trips and spirited back-road runs. As for the S6's trunk, its 14.1-cubic-foot volume is a little below average for this segment, but it has a useful rear seatback that folds down in a 60/40 split and includes a pass-through opening for carrying long items such as skis.