With one exception, Audi AG is having a great year.

It now is running neck-in-neck in global sales with German-rivals BMW AG and Mercedes-Benz. In the U.S., it is poised to sell more than 100,000 vehicles for the first time ever, with most of its models flying out of showrooms.

But there is one key slice of the U.S. market Volkswagen AG’s luxury unit just can’t seem to cut into: the U.S. upper-luxury-sedan segment.

Through November, the auto maker had sold just 1,013 of its previous-generation A8, down 18% while every other player, thanks to newer or brand-new models, was up substantially.

The Mercedes S-Class (+26%), BMW 7-Series (+37%) and Lexus LS (+16%) dominate this niche, which is rounded out with smaller-volume players such as the Jaguar XJ and Porsche Panamera, whose sales of 3,709 and 7,041 units, respectively, through November are brisk after being launched late last year.

Through November, Mercedes delivered 12,639 S-Class models, BMW sold 11,229 7-Series sedans and Lexus delivered 10,759 LS sedans, according to Ward’s data.

The all-new, fourth-generation ’11 A8, which hit showrooms in late November, has a shot at significantly improving future sales. But the chances of overtaking either of its German rivals are slim. Sales of the Audi flagship peaked at 6,000 units in 2004.

It took BMW 25 years to be seen as Mercedes’ equal in the large sedan market. It may take Audi almost as long – at least in the U.S.

It won’t be for lack of trying. The new A8 is a big, gorgeous car with superb engineering and a sumptuous, highly crafted interior.

In front, the car sports an enormous grille and full LED headlamps, turn signals and taillamps that cause pedestrians to stare. Unfortunately, aside from the front view, the rest of the car’s lines are quite plain.

The interior is a feast for the senses, though, with rich, supple materials and eye-pleasing textures and colors everywhere.

Designers even went out of their way to make everyday details look like highly crafted artwork. A key example is the so-called “Koenigsfuge” or “King’s Joint,” where the door and dashboard meet.

Instead of trying for a simpler solution, stylists chose to have four different materials and design lines converge at this joint, including plastics, the leather instrument panel cover and both wood and aluminum inlays.

This is inviting potential production trouble because any slight misalignment of the door or dashboard will be multiplied four times and look terrible. But it looks beautiful because everything lines up perfectly.

The Kings Joint is one of several examples where Audi engineers and designers deliberately used a more difficult solution to show off craftsmanship and manufacturing quality.

’11Audi A8 (standard wheelbase)
Vehicle type Front-engine, all-wheel-drive, 4-door sedan
Engine 4.2L DOHC DI V-8 with aluminum block/heads
Power (SAE net) 372 hp @ 6,800 rpm
Torque 328 lb.-ft. @ 3,500 rpm
Transmission 8-speed automatic
Wheelbase 117.8 ins. (299 cm)
Overall length 202.0 ins. (513 cm)
Overall width 76.7 ins. (195 cm)
Overall height 57.5 ins. (146 cm)
Curb weight 4,409 lbs. (2,000 kg)
Base price $78,050
Fuel economy 17/27 mpg (13.8-8.7 l/100 km)
Competition Mercedes S-Class, BMW 7-Series, Lexus LS, Jaguar XJ, Porsche Panamera
Pros Cons
Grille, HED headlamps Exterior too conservative
Stunning interior Lacks Audi flair
Innovative, intuitive HMI Not that lightweight

The result is an interior so captivating the driver wants to spend a few minutes each day exploring every nook and cranny of the doors and dashboard with their eyes and fingertips before starting the car.

Thankfully, Audi engineers did not use the-more-complicated-the-better philosophy for the vehicle electronics.

Instead, the A8’s central electronic controller, an axis of frustration in many luxury cars, is surprisingly simple and intuitive. It features a touch-sensitive pad that recognizes handwritten letters and numbers for navigation destinations.

Anyone who has struggled with the usual tiny buttons, dials or other types of controllers used to input destination data will appreciate this system’s simplicity.

It is backlit and can change to a pointer for map functions. And most interesting from a design and engineering standpoint, the system recognizes a wide variety of languages, including Cyrillic, Cantonese, Japanese and Korean characters.

Audi also claims the A8 is first to offer wireless access for electronic devices such as iPads and laptops.

The car is filled with the usual array of safety and convenience options found in this segment, plus a mind-numbing list of options, from massaging seats to a $6,000 Bang & Olufsen audio system.

The A8 is powered by Audi’s mellifluous 4.2L direct-injection V-8, which makes 372 hp and 328 lb.-ft. (445 Nm) of torque. Linked to an 8-speed automatic transmission, it reaches 62 mph (100 km/h) in 5.7 seconds.

That’s plenty fast in a huge sedan, but as good as Audi’s V-8 is, it pales before BMW’s 4.4L turbocharged V-8 that makes 400 hp and a whopping 450 lb.-ft. (610 Nm) of torque.

Audi always has tried to differentiate the A8 from its competitors with engineering features such as all-aluminum construction and standard all-wheel drive.

The relative lightness of the car is somewhat noticeable during hard cornering and acceleration, and AWD always is a bonus in cold-weather states.

New this year is an optional torque-vectoring differential that Audi says noticeably reduces understeer and increases driving agility and traction.

But Audi now has to share aluminum-body honors with the Jaguar XJ, which in its rear-drive- only configuration is more than 360 lbs. (163 kg) lighter.

And while Audi brags that “sportiness” is a key differentiator from its competition, steering and braking are not as razor sharp as the BMW, even though an AWD-equipped 7-Series is about 300 lbs. (136 kg) heavier.

On the other side of the equation, the A8 does not have the kind of signature “bank vault” feel of the S-Class while cruising on the expressway. It does have an air-suspension system that allows the driver to dial in different states of tune, but none seems as satisfying as that offered by BMW or Mercedes.

After driving the A8 on Detroit’s potholed streets for a week, we also found the A8’s ultra-stiff all-aluminum body a bit harsh at times, sometimes transmitting road jolts directly to our molars despite the best efforts of the tires and suspension.

Steel, indeed, is heavier than aluminum, but it also has ductility that allows for a softer ride.

In short, viewed in a vacuum, the new A8 is a magnificent car. But compared with its extraordinary competitors, it comes up a little short in styling, presence and overall personality.

And while many individual pieces of the A8 are best in class, from the stunning front end to the interior, they don’t meld together to provide the ultimate driving experience required in this Olympian segment.

It seems Audi has figured out how to conquer every other luxury-vehicle niche, from the entry level A3 to Ferrari-competitors such as the R8, but it still needs to work on the large luxury sedan sector.

If Audi wants to convince wealthy consumers to abandon their beloved S-Class and 7-Series, the success of the more distinctive Jaguar XJ and Porsche Panamera show it needs a sedan that is not as conservative as the A8.