We've been hearing about "coupes" like the four-door 2014 Audi A7 for years now, and we're still perplexed. Try as they might, the Germans will never convince us that a coupe can have as many doors as a sedan. Nonetheless, the athletic A7 does a decent coupe impression from behind the wheel, and its sloping roof line admittedly brings old Mustang fastbacks to mind. We're prepared to concede that "coupelike" is a fair term for Audi's slinky head-turner.

Enhancing the A7's appeal for 2014 is the arrival of an optional turbocharged diesel V6. Fuel economy is outstanding at 29 mpg in combined driving, but that's only half the story. The A7 TDI can also scoot to 60 mph in an estimated 5.5 seconds, putting it in a virtual dead heat with the gasoline-powered A7 3.0T. It's hard to think of a better combination of fuel economy and acceleration on the market today, and the TDI engine's remarkable refinement makes it almost indistinguishable from a gas engine in normal operation. It will take a few years to recoup the TDI's higher up-front cost, and you'll likely have to grab an oily truck-stop pump handle from time to time, but for the most part, there's really no downside to buying the diesel Audi A7.

Underneath its seductive shell, the 2014 Audi A7 is largely derived from the more mainstream A6 sedan, and that's a good thing. Interior design and quality are beyond reproach, while the newly standard Audi Connect system turns the A7 into a rolling Wi-Fi hotspot. Unlike the A6, however, the A7 features a hatchback-style power liftgate that's more useful than a standard sedan trunk. The trade-off is diminished rear headroom, an unavoidable consequence of the A7's coupe-style roof line.

Competition in this exclusively German segment is fierce, beginning with the "coupe" that started it all, the 2014 Mercedes-Benz CLS-Class. Aggressive styling and stellar twin-turbo V8 power continue to set the CLS apart, while BMW has recently gotten into the act with the similarly appealing 2014 BMW 6 Series Gran Coupe. The 2014 Porsche Panamera offers even more performance, although it costs more, and its styling remains a matter of taste. You can't go wrong, as these are all truly world-class cars.

But we can see how the A7 might emerge victorious. It's got beauty on its side, which never hurts, and the new turbodiesel model is a uniquely tempting proposition. We'll never call it a coupe, but dollar for dollar, the 2014 Audi A7 is one of the best cars you can buy.

The 2014 Audi A7 is available in one trim level -- Premium Plus -- for both the 3.0T and TDI engines. The higher-performance S7 and RS 7 are reviewed separately.

Standard equipment on the Premium Plus includes 19-inch wheels, adjustable drive settings, automatic bi-xenon headlights, LED running lights, a power liftgate, automatic wipers, heated windshield washers, heated and auto-dimming mirrors, a sunroof, front and rear parking sensors and keyless ignition/entry. Inside you'll find an auto-dimming rearview mirror, a tilt-and-telescoping steering wheel, tri-zone automatic climate control, leather upholstery, heated eight-way power seats (with four-way lumbar adjustment), driver memory functions, an 8-inch display screen, a rearview camera, a navigation system, Audi's MMI console-mounted electronics controller, voice controls, Bluetooth phone and audio connectivity, Audi Connect (enhanced Web-based navigation, information and Wifi access) and a 10-speaker audio system with a CD player, satellite radio and an iPod interface.

The optional Prestige package adds adaptive headlights, sportier exterior trim, a blind-spot warning system, a rear-end collision warning system, LED ambient interior lighting, four-zone automatic climate control, ventilated front seats, a power-adjustable steering wheel and an upgraded 14-speaker Bose surround-sound audio system.

Most A7 options come bundled in various packages. The Cold Weather package includes heated rear seats and a heated steering wheel. The Sport package adds special 19-inch or 20-inch wheels, summer tires, a sport-tuned suspension and a sport steering wheel with shift paddles. Sport package models can be enhanced via the Black Optic package, which contributes 20-inch bi-color wheels and high-gloss black trim on the grille and window surrounds. The Driver Assistance package includes adaptive cruise control, a front collision warning system, a corner-view camera system (front and rear) and lane-departure warning/keeping assist. The Prestige is also eligible for the Innovation package, which is essentially the Driver Assistance package with an infrared night vision display and a head-up display.

Stand-alone options on the Prestige include LED headlights, power-closing doors and a 15-speaker Bang & Olufsen surround-sound audio system.

The 2014 Audi A7 offers a choice of two engines. The A7 3.0T comes with a supercharged 3.0-liter V6 that produces 310 horsepower and 325 pound-feet of torque, while the A7 TDI gets a turbocharged 3.0-liter diesel V6 that produces 240 hp and 428 lb-ft. An eight-speed automatic is the only transmission offered, and it sends power to all four wheels.

In Edmunds performance testing, the A7 3.0T accelerated from a standstill to 60 mph in 5.4 seconds, which is quicker than average for this class of car with a six-cylinder engine. Audi projects a similar sprint of 5.5 seconds for the A7 TDI, making it one of the most rapid diesel-powered cars on the road.

The 3.0T is EPA-rated at 21 mpg combined (18 mpg city/28 mpg highway), which is a couple mpg fewer than an all-wheel-drive 640i Gran Coupe. But you won't find better fuel economy in this class than the A7 TDI, as it checks in at an impressive 29 mpg combined (24 city/38 highway).

Standard safety equipment on the 2014 Audi A7 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 A7'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 rear collision, employing additional preventive protective measures should the situation turn critical.

In Edmunds brake testing, an A7 Prestige with 20-inch wheels and summer tires came to a stop from 60 mph in 106 feet. That's impressive even for summer tires; expect a longer distance for the regular tires and smaller wheels.

Were it not for the new turbocharged diesel V6 engine, we'd just keep raving about the 2014 Audi A7 3.0T's strong supercharged V6. Low-end power is abundant and always at the ready, yet the 3.0T likes to rev, too, pulling to redline with gusto. The quick-acting eight-speed automatic transmission only adds to the car's responsive character.

But this year, at least, the A7 TDI is the center of attention, delivering one of the most thrilling diesel driving experiences yet. With over 100 more pound-feet of torque than the gas engine, the TDI V6 blasts away from stoplights and dispatches highway dawdlers with ease. This is a genuine high-performance car that just happens to use diesel fuel instead of gasoline.

Every A7 comes with Audi's Drive Select feature, which alters throttle response, transmission shift characteristics and steering effort based on four different modes: Comfort, Auto, Dynamic and Individual. We've found it a challenge to dial in exactly the right settings for our taste, and the steering feel doesn't impress us in any of the settings. Still, the A7's handling is rewarding, as this luxury hatchback has a nimble, athletic feel that belies its hefty curb weight. Just watch the ride quality with the available 20-inch tires; the A7 already rides firmly by default, so sticking with the smaller 19s might be a better bet if you value a supple ride.

The A7's interior is typical Audi, which means both handsomely designed and tightly constructed, with excellent materials quality evident throughout. Audi's familiar Multi Media Interface system (MMI) controls entertainment, communication and navigation functions via a dash-mounted pop-up screen and a knob and 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 A7 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.

Due to the A7's aggressively raked roof line, backseat headroom is tight, even for adults of average height. Legroom is adequate, however, and the newly standard three-across seating raises passenger capacity to five in a pinch. The A7's hatchback design enables easy loading of luggage and larger items that might not fit in the trunk of a conventional sedan. Official cargo capacity is 24.5 cubic feet, but lowering the rear seatbacks increases that volume significantly.