Four doors typically signify compromise in the world of high-performance cars. So does the use of underpinnings borrowed from the rather commonplace A6 sedan. But even though the 2016 Audi RS 7 has both, this hot-rod hatchback still has the goods to get any enthusiast's heart racing. With a 560-horsepower turbo V8, an advanced all-wheel-drive system and seductive styling, the RS 7 is a genuine thrill ride that just happens to have room for four adults and their luggage.

The only problem is that much the same could be said of the "regular" S7, which packs a twin-turbo V8 of its own and costs a whole lot less. The savvy shopper's question, then, is what exactly you get for that extra suitcase full of cash. For one thing, the RS 7 gains 110 hp under the hood, increasing the 450-hp S7's already stupendous speed by a factor of OMG. Between the wheels, there's an RS-specific active sport suspension if you specify the Dynamic package, though of course that costs even more. The RS 7 also boasts a number of unique exterior and interior trim elements, including gaping front air intakes that give the car a subtly sinister look. Then there's the eight-speed conventional automatic transmission, which supplants the S7's excellent seven-speed dual-clutch automated manual.

Wait, what? Alas, it's true. Although the dual-clutch gearbox generally serves duty in Audi's sportiest models (including the exotic R8), it couldn't handle the RS 7's increased torque output, so a regular automatic had to suffice. To be clear, the ZF-built eight-speed that seemingly everyone's using these days is a wonderful unit that drew rave reviews in our RS 7 track test; owners are quite unlikely to be disappointed. But if you look at BMW's lineup, for example, it's the M6 Gran Coupe that gets the racy automated manual setup, not the 650i Gran Coupe with its lesser engine.

Nonetheless, you probably won't be pining away for a different transmission when you're sprinting to 60 mph in 3.4 seconds. If the 2016 Audi RS 7 isn't the fastest four-door on the planet, it's certainly in the conversation, and that's the name of the game in this league. The Porsche Panamera Turbo is roughly as quick in a straight line and nimbler going around corners, but it's more expensive and arguably less attractive. The Mercedes-Benz CLS63 AMG and the aforementioned BMW M6 Gran Coupe can hang with the RS 7 in spirited driving, but they lack the Audi's hatchback versatility. You might also consider the Tesla Model S if you're open to going electric. But for uncompromised speed in a stylish yet functional package, it's tough to top the Audi RS 7.

The 2016 Audi RS 7 comes in a single well-equipped trim level that's similar to the Prestige trim of the regular Audi A7, albeit with a number of performance-themed upgrades. Unlike the A7 sedan, which has a three-passenger rear seat, the RS 7 has two individual rear seats, meaning a limit of four passengers instead of five.

Standard features include 20-inch wheels, LED headlights and taillights, a sport body kit, an adaptive sport-tuned air suspension, variable-ratio steering, a sport differential, a sunroof, a power liftgate, auto-dimming mirrors, front and rear parking sensors, a basic collision mitigation system (Pre-Sense Basic and Pre-Sense Rear), a blind-spot monitor and keyless entry and ignition.

Inside you'll find ambient LED lighting, leather upholstery, heated eight-way power front sport seats (with four-way lumbar adjustment), a power tilt-and-telescoping steering wheel, driver memory settings, four-zone automatic climate control, Audi Drive Select (providing driver control over steering, suspension, transmission and exhaust calibrations), Audi's MMI technology interface (with a console-mounted controller that includes touchpad functionality), an 8-inch display screen, a rearview camera, voice controls, a navigation system, a head-up display, Bluetooth phone and audio connectivity, Siri Eyes Free, Audi Connect (including 4G LTE connectivity, WiFi hotspot capability and Web-based navigation and information services) and a 14-speaker Bose audio system with a CD player, satellite and HD radio and an iPod interface.

There are numerous options packages available for the 2016 Audi RS 7. The Driver Assistance Plus package adds automatic high beams, adaptive cruise control, lane departure warning/keeping assist, a corner-view (front and rear) parking camera system and the upgraded Pre Sense Plus collision mitigation system with automatic braking. The Dynamic package adds a sport exhaust with black tailpipes, red-painted brake calipers and a "Dynamic Ride Control" active sport suspension that replaces the air suspension.

The Comfort Seating package features different leather upholstery (lacking the standard honeycomb stitching), "contour" front seats (with ventilation and massage functions), passenger memory settings and comfort rear seats. The Cold Weather package adds heated rear seats and a heated steering wheel. Finally, there are several Optic packages that alter the finish and appearance of the car's mirrors, grille, lower air intakes and rear diffuser.

Stand-alone options include 21-inch wheels, power-closing doors, a night vision system, a simulated suede headliner, rear side airbags and a 15-speaker Bang & Olufsen surround-sound audio system.

The RS 7 is powered by a turbocharged 4.0-liter V8 that sends 560 hp and 516 lb-ft of torque to all four wheels. An eight-speed automatic transmission, a self-locking center differential and a sport rear differential are standard.

During Edmunds performance testing, an RS 7 leapt to 60 mph in an absurdly quick 3.4 seconds, which is more than half a second quicker than a Chevrolet Corvette. According to the EPA, the RS 7 returns 19 mpg combined (16 city/27 highway), remarkably frugal numbers for this level of performance.

Standard safety equipment on the 2016 Audi RS 7 includes antilock disc brakes, stability control, front and rear parking sensors, a rearview camera, a blind-spot warning system, front-seat side airbags, full-length side curtain airbags and front knee airbags. The standard Audi Pre Sense Basic collision mitigation system tightens the seatbelts and closes the windows if a potential frontal collision is detected, while the Pre Sense Rear function scans for potential rear collisions.

Rear side airbags are a stand-alone option, while the optional Driver Assistance Plus package includes lane-departure warning and lane-keeping assist, night vision with pedestrian detection, a corner-view parking camera system, adaptive cruise control and Audi Pre Sense Plus, which can automatically apply the brakes to mitigate the severity of an imminent crash.

In Edmunds brake testing, the Audi RS 7 stopped from 60 mph in a short 108 feet.

The 2016 Audi RS 7 is masterful in almost every conceivable driving scenario. At a steady highway cruise, there's hardly any ambient noise. It's also one of the quietest cars we've ever tested at 70 mph, which is all the more remarkable when you look at the RS 7's enormous (read: noise-generating) tires. But with a simple tap of your toe, the transmission seamlessly switches gears, the exhaust bellows menacingly (more so with the Dynamic package's sport exhaust) and a wave of turbocharged torque shoves you back into your seat for as long as you dare. Few cars can match the RS 7's one-two punch of confident luxury and face-flattening acceleration.

Around turns, the RS 7 is stable and capable of extraordinary grip. It's a big car, yet the all-wheel drive and torque vectoring diff also allow you to power out of corners with surprising ease. It's only in full-attack mode on really tight roads or a racetrack that the car's inherent forward weight bias rears its head, resulting in some occasionally tricky handling behavior at the limit.

The RS 7 typifies Audi's leadership in interior design, displaying eye-pleasing details, tight construction and excellent materials throughout. It also benefits from RS-specific carbon-fiber inlays, aluminum pedals, many other RS-themed flourishes and ambient LED lighting. Audi's familiar Multi Media Interface (MMI) system controls entertainment, communication and navigation functions via a dash-mounted pop-up screen and a control dial surrounded by buttons on the center console. The system features logical menus, crisp graphics and a touchpad to increase functionality, as well as 4G LTE connectivity with WiFi to enhance online activities on the go. Other systems like BMW's iDrive are a bit easier to learn, but once you've got the hang of things, the MMI system is one of the best available.

Whether you stick with the standard front sport seats or opt for the Comfort Seating package with its massaging "contour" seats, you'll enjoy superlative support during long trips and spirited back-road runs alike. Due to the RS 7's aggressively raked roofline, however, backseat headroom is tight even for adults of average height. Legroom is abundant, however, and there's something to be said for the individual comfort of the twin rear bucket seats versus the regular A7's traditional three-across bench seat (the S7 also has twin rear seats).

The RS 7's hatchback design enables easy loading of larger items that just won't fit through the trunk opening of a conventional sedan. The space itself is generous, too, measuring 24.5 cubic feet behind the rear seatbacks. That's roughly 10 cubic feet more than rivals like the CLS with normal trunks. Notably, you can also fold the RS 7's rear seatbacks forward to open up a significantly larger space.