Breathtaking design takes priority on the 2014 Mercedes-Benz CLS-Class. A "four-door coupe" variation on the related E-Class, the CLS is easily one of the most attractive luxury sedans on the market, and it's one of those cars that looks even better in person than in photos. It's powerful, too, with two different, turbocharged V8s that make driving it an exhilarating experience. Among this Mercedes-Benz's few downsides are its relatively high price tag and its dramatically sloping rear roof line, which limits the car's versatility.

These limitations are readily apparent in the CLS-Class sedan's backseat, which can accommodate only two passengers and isn't comfortable for full-size adults. The car's high beltline and small rear windows make it feel even smaller, and compared to the more conventional E-Class sedan, you lose a full inch of rear headroom.

The situation is much different up front, as there's plenty of room to stretch out in the luxurious cockpit. If you're in the driver seat, your mind will be further occupied by the engine under the hood. With 402 hp on tap, the standard CLS550 is an amazingly quick luxury sedan in its own right. Meanwhile, the CLS63 AMG enters the realm of ridiculous speed with 550 hp in standard form and 577 on the S-Model. The switch to all-wheel drive (from rear-wheel drive) for 2014 changes the CLS63's character slightly, but it makes the car more of a year-round proposition for buyers in cold climates.

Of course, there are plenty of luxury sedans that offer many of the same advantages as the 2014 Mercedes-Benz CLS-Class. The 2014 Audi S7 (and the ultra-high-performance RS 7) and 2014 BMW 6 Series Gran Coupe (along with the M6 Gran Coupe variant) represent a more practical take on the four-door coupe trend (they have more rear seat room) and feature powerful V8s of their own.

Other possibilities include the Jaguar XF, which has a much wider range of engines, and the 2014 Porsche Panamera, which is not exactly beautiful but is certainly the best-handling car in this group. Another interesting option is the all-electric Tesla Model S, which offers similar quickness and makes a design statement of its own.

Ultimately, any of these cars would be satisfying to own, and if you're drawn to the high style and raw speed of the 2014 Mercedes-Benz CLS-Class, we won't stand in your way.

The 2014 Mercedes-Benz CLS-Class is a four-passenger, four-door midsize luxury sedan. The CLS550 is available in rear-wheel-drive and 4Matic all-wheel-drive variations, while the 4Matic-only CLS63 AMG is offered in base and S-Model versions.

The CLS550 and CLS550 4Matic come standard with 18-inch wheels; all-season tires; an adaptive air suspension; bi-xenon headlights; LED running lights; auto-dimming rearview and side mirrors; a sunroof; dual-zone automatic climate control; 10-way power front seats with heating, memory functions and four-way lumbar adjustment; a power tilt-and-telescoping steering wheel and leather upholstery. Electronics features include a 7-inch video display with the COMAND infotainment interface; a navigation system; voice control; Bluetooth phone and audio connectivity; Mercedes' mbrace2 telematics system and a 14-speaker Harman Kardon surround-sound audio system with a six-CD changer, HD radio, satellite radio, USB/iPod integration and an auxiliary audio input.

The CLS63 AMG adds a more powerful twin-turbo V8, a different transmission, 19-inch wheels, summer performance tires, a sport-tuned adaptive suspension, a sport steering wheel with shift paddles, upgraded leather upholstery, a power rear sunshade and a split-folding rear seat (optional for the CLS550).

The CLS63 AMG S-Model gains additional power, a higher top-speed limiter (186 mph instead of 155), a more aggressively tuned suspension, a limited-slip differential, launch control, a different set of 19-inch wheels with a titanium finish, a carbon-fiber engine cover and rear spoiler, red brake calipers, a unique leather interior, and simulated suede trim on the steering wheel.

Available on all models, the Premium 1 package adds adaptive LED headlights with automatic high-beam control, a rearview camera, a power trunk closer, keyless ignition/entry and ventilated front seats. On the CLS550, this package also includes a power rear sunshade. The CLS63 version includes front seats with active bolsters and massage.

The Lane Tracking package adds a blind-spot warning system and a lane-departure warning system. The Driver Assistance package gets adaptive cruise control and enhanced, active versions of the Lane Tracking items. The Parktronic package includes front and rear parking sensors and an automatic parking system. Stand-alone options include an infrared night-view display, heated rear seats and a premium Bang & Olufsen surround-sound system. The CLS550 can also be equipped with a 19-inch AMG wheel package that includes summer tires and paddle shifters, as well as stand-alone options like a heated steering wheel and massaging front seats with active bolsters. Carbon-ceramic brakes are optional on the CLS63 S-Model.

The 2014 Mercedes-Benz CLS550 is powered by a twin-turbocharged 4.7-liter V8 that sends 402 hp and 443 lb-ft of torque to the rear wheels through a seven-speed automatic transmission. On the CLS550 4Matic, power goes to all four wheels through an all-wheel-drive system.

In Edmunds performance testing, a rear-wheel-drive CLS550 went from zero to 60 mph in 4.6 seconds -- truly impressive performance for a V8-powered sedan of this size. EPA-estimated fuel economy is 20 mpg combined (17 mpg city/25 mpg highway) for the rear-drive CLS550, while 4Matic is rated at 19 mpg combined (17 mpg city/24 highway).

The CLS63 AMG gets a twin-turbo 5.5-liter V8 that makes 550 hp and 531 lb-ft of torque, and a specialized seven-speed automatic transmission sends power to all four wheels through its standard AWD system. If that's not good enough, the CLS63 AMG S-Model pumps out a massive 577 hp and 590 lb-ft of torque, thanks to a slight increase in turbo boost pressure and revised engine software. Estimated fuel economy on both versions of the 2014 Mercedes-Benz CLS63 AMG is 19 mpg combined (16 city/25 highway).

Every 2014 Mercedes-Benz CLS-Class features standard four-wheel antilock disc brakes, traction and stability control, front knee airbags, front side airbags (both torso and pelvic), full-length curtain airbags and the Mercedes-Benz mbrace2 telematics system (smartphone integration and Web-based apps that include remote controls, driver monitoring and emergency services). Also standard is Attention Assist (a driver drowsiness and alerting monitor) and PreSafe (it anticipates an imminent crash and automatically takes measures to better secure occupants).

Options include rear side airbags, infrared night-view sensors and rearview parking sensors. The Driver Assistance package adds blind-spot and lane-departure systems; the active version of this package takes action should you fail to heed those warnings. A rearview camera is also optional.

In Edmunds brake testing, a CLS550 with optional summer tires came to a stop from 60 mph in 108 feet, which is excellent but just a tad better than average for the class.

Simply put, the 2014 Mercedes-Benz CLS550 drives beautifully. The adaptive air suspension and variable dampers provide secure handling and an impressive ride quality. The electrically assisted steering offers good feedback, loads up naturally and quickens the more you turn, making the CLS feel smaller than it actually is. Also helping that effort is a "base" engine that utterly flattens you into your seat with a simple brush of the pedal. It's hard to imagine needing any more power.

But you might not need to imagine very hard once you've dropped yourself into the CLS63 and feel its glorious, twin-turbo V8 at work. This is a truly majestic power plant, and it's complemented by a transmission that swaps gears with surgical precision.

The addition of standard all-wheel drive on the 2014 CLS63 AMG makes it a more capable car for buyers living in cold climates. We haven't driven the 4Matic version of the CLS63 yet, but based on our experience with the E63 AMG 4Matic, the AWD system should enhance control on dry pavement as well.

As with the exterior, the CLS cabin takes the current Mercedes-Benz design aesthetic and makes it more organic and curvaceous. Materials are beyond reproach. The control layout is similar to the E-Class, though the CLS swaps in an analog clock and the older knob-style climate controls in lieu of newer toggle buttons. Stepping up to the CLS63 4Matic adds a chunky AMG wheel and fills the center console with AMG vehicle controls and the MCT transmission selector (complete with an embossed AMG crest) in lieu of the 550's electronic shift lever on the steering column.

With its low, racy roof line and two-passenger backseat, the 2014 Mercedes CLS isn't an ideal people carrier. If you frequently ferry people around or have particularly tall friends, opting for the less expensive E-Class is probably a wiser idea. Trunk space is pretty generous, however, with 15.3 cubic feet available.