The Audi A6 is a study in excellent design. Flowing lines give the A6 sedan the sleekness of a coupe without the quashed windows and head-enveloping window line. There's simplicity to the upswept door trim and shoulder crease blending into a subtle rear spoiler that suggests elegance and strength. Jewelry and adornment are kept to a minimum; as with an attractive person no additional cosmetics are needed.

A trapezoidal grille and substantial interlocked rings highlight the front end, so that the grille pattern continues top to bottom, eliminating the flat license-plate section that spilt the opening on pre-2009 models (although in states that require a front plate, there really isn't any other place for it go). Rectangular fog lamps enhance the front styling, and a strip of LED running lamps underlines the headlight housing. At the rear of the A6 are sleek, oblong LED taillights.

The A6 Avant is an especially sleek-looking wagon, distinguished by dark center pillars, very mildly tapering side windows and sloping roofline with discrete spoiler incorporating the center brake light. The hatch glass angle is more crossover-like, as opposed to a Volvo wagon's upright box rear end; the defroster will quickly shed snow.

Body panels fit closely together on the A6, around the doors, hood and trunk lid, along lamps and door handles. It's the look of quality, of close tolerances, as is the reassuring thud when you close anything. You won't even find a rubber strip at the top of windshield, nor strips on the sides of the roof. Door jambs and the trunk and hatch openings are all well-finished, and there are myriad seals to keep dirt and wind noise out. Audi is superior to Mercedes at these sorts of details.

A large color palette and multiple wheel styles and sizes (17-19 inches) help buyers personalize each A6. The 19-inch wheels on the Avant lend the appearance of Audi's 174-mph RS6 superwagon.

The S6 is distinguished from its less-powerful stalemates by special exterior and interior elements. Most noticeably, it retains the old-style split grille, albeit overlaid with a grid-like pattern. A different front bumper feeds more cooling air and moves the LED daytime running lights to the top of two lower cooling ducts. The front foglamps are incorporated into the headlight housings with tinted covers, the lower door trim is more pronounced, and the integrated trunk spoiler is a bit larger. The aluminum trim surrounds rearview mirror housings. The S6 also has black brake calipers, dual tailpipes each side, special 19-inch wheels with fat tires, and the requisite S6 and V10 badges. Paint choices are limited to a more discrete palette, a good move as the exhaust note attracts enough attention.

Interior

The Audi A6 cabin is spacious, very well finished, and bathed in daylight. While no one builds the perfect interior, Audi is frequently recognized for its interiors.

Valcona leather upholstery is standard across the A6 line, including a very attractive combination of amaretto and black. The amaretto on the seat centers is surrounded by black, and on the door panels makes a nice counterpoint to the also-standard wood trim. By making the dashboard black to avoid reflections and the carpet black to minimize showing dirt, they've made an elegant cabin that's four-season functional as well.

Metallic trim on the dash, air vents, door pulls and many controls is a matte aluminum finish that produces no glare; chrome is used very sparingly. Everything is illuminated, even the door armrests with light pipes hidden under the wood trim. Each door, the area above the glovebox, and the center console are finished in wood, our only concern that the side edges on the console may be more vulnerable to scuffs than leather or vinyl.

The front seats are comfortable, supportive and offer good power adjustment range; fatigue should never be an issue even with the A6's 500-mile cruising range. Wind, road and engine noise are quelled so conversation is easy, even when driving quickly.

The rear seats are comfortable, too. Head and leg room are expansive enough to tote around two clients in comfort even if you and they are all six feet or taller. Getting in and out of the back seats is relatively easy thanks to a back door much taller than most sleek sedans, space between the seat and door post that shames most full-size SUVs, and a foot space big enough to slide under the front seat. There are three adjustable headrests, reading lights that can't be seen in the driver's mirror, front seatback storage, and a split rear seatback that folds down with the narrow section behind the driver.

Up front, everything is oriented around the driver. The driver benefits from a nice four-spoke steering wheel or a nicer, sportier three-spoke wheel; both have thumbwheels and buttons for redundant control, and a clear view of analog instruments, but only the four-spoke wheel can be heated. The center dash, including the navigation screen, is slightly angled toward the driver. Climate controls are located at the bottom, sophisticated but straightforward and easy to operate. At the top of the stack, above the vents, is a crisp seven-inch screen that displays navigation and other functions. The standard trip computer and Driver Information Center features a digital speed indicator.

Audi's Multi Media Interface, or MMI, features a large knob and 15 buttons set horizontally on the center console to control most interior and many exterior functions. This eliminates a lot of switches, making for an uncluttered dash. Logical grouping eases the acclimation process, yet a few days and familiarization with the owner's manual will you allow you to master MMI quickly and appreciate what you can do with it. As with many new cars you can't just press-and-hold to program a radio preset but it does have a regular round volume knob. The main controller and buttons fall easily to hand right behind the shifter but are not accidentally bumped as on some such system. To ease access by the driver, the glovebox door button is located on the center of dash next to an Off switch for the screen.

High technology can also be found in what have been traditionally mundane controls. The parking brake is electronic; pull the switch up to set it, press to release it. The hood release operates only when the door is open, good to know. The wipers are speed sensitive. A Bluetooth-enabled interface integrates compatible equipment. The rear camera is predictive, showing where the car will go as the steering wheel is turned. And the trunk and fuel door release buttons are in the door pocket and since you have to lift, not push them, there are no mistakes dropping your phone or sunglasses case in the pocket.

The A6 does not offer many places to put stuff, an inconvenience. The glovebox is small, especially with the available CD changer and the center armrest storage isn't capacious, but door pockets help. The cup holders are positioned well and contain beverages in spirited driving.

The trunk is deep enough for a 24-inch roller suitcase. Luggage capacity is nearly 16 cubic feet, more than a BMW 5 series or Acura RL and comparable to the Mercedes E-Class, and it is shaped like most suitcases, with 90-degree angles. Details include plenty of tie-down points, bag hangar hooks, a strap to hold the floor up for access, and a rarity these days, a full-size matching spare alloy wheel and tire.

The Avant sport wagon offers essentially the same floor layout as the sedan but with the added space afforded by the extra height. An overlooked side benefit of the wagon is that the rear window doesn't fog up as quickly. The luggage compartment offers a variety of configurations and features two securing rails recessed into the floor and four D-rings adjustable over the rail length. The cargo area cover also has a roll-up net to keep cargo or the dog separate from the passengers, and light is sufficient for night loading. Various nets, hooks, straps and posts handle cargo retention duty. The load floor can be folded up and locked in several ways, which provides access to a lower load area lined by a plastic tray, an ideal cubby for stowing wet or muddy gear, and again, a full-sized matching spare.

The rear hatch opening of the Avant is roughly 42 inches wide by 29 high, and with the rear seats folded the cargo bay is more than six feet long. Powered hatches may be programmed to stop at any height, such as in low-ceiling residential garages, and a groove to grab the bottom of the hatch runs the entire width of it, rather than just one or two hand pockets.

The S6 cockpit features integral-headrest, heavily bolstered sport seats upholstered in Nappa leather. However, the standard seats in Milano leather are available for folks who might find the sport seats too confining. The three-spoke, power-adjustable sport steering wheel is trimmed in smooth leather and has a color-contrasting double-stitch. The S6 features unique instrument graphics and badging. Aluminum shift paddles and console shifter knob provide a high-tech contrast to the standard gray birch trim or optional carbon fiber inserts. The S6 offers the same cabin and trunk space as an A6 sedan.