If you're a prospective 2014 Audi S7 owner, the question isn't how much speed you need, but rather how much you crave. Because let's be honest: No one really needs more than the regular A7's 310-horsepower supercharged V6. If you sample the S7's 420-hp V8, though, you're probably going to crave it. Once you feel the S7's otherworldly turbocharged punch, the extra 20 grand or so that Audi charges might even seem like a reasonable price to pay.

Of course, the S7 isn't just an A7 with more motor. For one thing, it comes standard with a seven-speed automated manual transmission that isn't even offered on its lesser-priced sibling. For another, its exclusive sport-tuned air suspension magically smoothes out the A7's somewhat busy ride while also improving handling. Then, there's the usual assortment of subtle S-model badging and styling cues, not to mention a trick sport differential that can transfer power from one rear wheel to the other. What's more, many of the A7's desirable options come standard here.

The S7's sleek, coupelike shape makes it a natural rival to the BMW 650i Gran Coupe and the Mercedes-Benz CLS550, which boast turbocharged V8s of their own. Compared to the surprisingly affordable Mercedes, the S7's backseat feels more cramped, while the costlier BMW pumps out 480 pound-feet of torque to the S7's 406. But the S7 feels nimbler and more athletic than its competitors, and its combination of performance, style, technology and hatchback convenience is hard to top at any price. You may not technically need a 2014 Audi S7, but we'll forgive you for thinking otherwise once you get behind the wheel.

The 2014 Audi S7 comes in a single well-equipped trim level. Unlike the A7, which comes in a five-passenger configuration for 2014, the S7 has two individual rear seats, meaning a strict four-passenger capacity.

Standard features include 19-inch wheels, adaptive xenon headlights, an adaptive air suspension, a sport differential, a sunroof, a power hatchback, keyless ignition/entry, heated and auto-dimming mirrors, front and rear parking sensors and a blind-spot warning system. Inside, you'll find Audi Drive Select (providing driver control over steering, suspension and transmission calibrations), diamond-stitched leather upholstery, eight-way power heated front sport seats (with driver lumbar adjustments), a power tilt-and-telescoping steering wheel, driver memory settings, four-zone automatic climate control, Audi's MMI console-mounted electronics controller, an 8-inch display screen, a rearview camera, voice controls, a navigation system, Bluetooth, Audi Connect (enhanced Web-based navigation, information and Wi-Fi access) and a 14-speaker Bose audio system with a CD/DVD player, HD radio and iPod connectivity.

Options for the S7 include a number of packages. The Innovation package features a head-up display and night vision assist, while the Driver Assistance package adds adaptive cruise control (with stop-and-go functionality), lane departure warning/keeping assist, a corner-view front and rear camera system and the Audi Pre-Sense Plus collision mitigation system. The Comfort Seating package features multicontour front seats with ventilation and massaging functions, passenger memory settings, comfort rear seats and leather upholstery with diamond stitching. The Cold Weather package adds heated rear seats and a heated steering wheel. Finally, the Black Optic package tacks on 20-inch 7-spoke wheels, body-color exterior mirrors (instead of the standard silver ones), a blacked-out grille and gloss black window surrounds.

Individual option highlights include 20-inch wheels, LED headlights, power-closing doors, a faux suede headliner, rear side airbags and a 15-speaker Bang & Olufsen surround-sound audio system.

The S7 is motivated by a turbocharged 4.0-liter V8 that sends 420 hp and 406 lb-ft of torque to all four wheels. Shifting duties are handled by a seven-speed automated manual transmission (S tronic).

According to Audi, the S7 can sprint from zero to 60 mph in just 4.5 seconds. Fuel economy is also highly respectable at 20 mpg combined (17 city/27 highway).

Standard safety equipment on the 2014 Audi S7 includes antilock disc brakes, stability control, front-seat side airbags, full-length side curtain airbags and front knee airbags. Rear side airbags, front and rear parking sensors, lane departure warning/keeping assist and a blind-spot warning system are either optional or included with the upper trims.

The standard Audi Pre-Sense system can warn the driver, tension the seatbelts and close the windows if a potential collision is detected, while the optional Audi Pre-Sense Plus system can do all that, plus fully tighten the seatbelts and automatically apply the brakes full force to mitigate the severity of an imminent crash. The S7's Prestige trim also comes with Audi Pre-Sense Rear, which uses the brake light to warn traffic behind the vehicle in the event of a potential rear collision, employing additional preventive protective measures should the situation turn critical.

The 2014 Audi S7 is a very powerful car, and the turbocharged V8 is always at the ready. With Audi's excellent automated manual transmission along for the ride, the S7 can claim one of the most responsive and satisfying powertrains on the market. The standard air suspension delivers a smooth ride along with sports-carlike handling, a deft balancing act that once again sets this Audi apart. From behind the wheel, the S7 feels more like a tautly proportioned coupe than its rivals, giving the driver confidence in both enthusiastic cornering and evasive maneuvers. Few four-door cars can match the S7's broad range of dynamic abilities.

The S7's interior is typical Audi, as it's handsomely designed and tightly constructed with excellent materials quality throughout. 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 boasts logical menus, crisp graphics and a touchpad to increase functionality, although we still prefer BMW's iDrive or Mercedes' COMAND for overall ease of use.

The S7 is also equipped with the Audi Connect Internet suite, which includes in-car 3G Wi-Fi, Google Earth data for the navigation system and simplified Google search for POIs. It sounds a bit over the top, but proves very handy if you need to get some work done on the road and there's no Starbucks in sight. However, the Google Earth feature is an example of form over function, as the "enhanced" map can be more difficult to comprehend at a glance than a conventional navigation map.

Whether you stay with the standard sport seats or opt for the multicontour comfort seats, we're confident you'll find them supportive during long trips and spirited back-road runs alike. But due to the S7's aggressively raked roof line, backseat headroom is tight for average-to-tall folks. Legroom is abundant, however, and there's something to be said for the comfort of the twin rear bucket seats versus a traditional three-across bench seat. The A7's hatchback design permits easier loading of larger items that just won't fit in the trunk of a conventional sedan. Official luggage capacity is 24.5 cubic feet, and lowering the rear seatbacks opens up more room.