Buyers in this class also are paying for cabin space and executive-class ambience. Again, the A8 delivers, particularly if they prefer their ambience in German hues. The cabin is trimmed with dark, rich walnut, and the gear selector is surrounded by brushed aluminum. Perforated leather upholstery feels thick and supple, and the elegant headliner looks like suede.

The A8's front seats are excellent, comfortable and supportive. Some cars offer a zillion adjustments, yet it's still hard to get comfortable in them. This car is comfortable from the outset.

A $3,500 premium leather option available only on the A8 L model adds leather on door panels, knee bolsters and the console.

The driver peers over a thick-rimmed steering wheel that's relatively small in diameter. The gauge cluster is back-lit in red and features an electronic message center. The turn signal stalk is spindly. At first glance, the center of the dash is a dazzling display of red-lighted buttons at night, but time spent with it builds familiarity.

His and hers climate controls tend to require minimal adjustment and are appropriately mounted below the stereo panel. The stereo buttons could be larger, but the largest of them is the volume control, square in the center where it's easy to find. The A8 has clever touches throughout. The latch for the glovebox is all the way left, within easy reach of the driver. Audi's overhead sunroof switch is the slickest going: Turn it a quarter, and the roof opens a quarter of the way. Turn it all the way, and the roof opens wide. An optional solar-panel sunroof ($850) available for the A8 L powers a fan to ventilate the A8 when it is parked.

The rear seats have variable lumbar support and headrest positioning, but lack the recline adjustment available in some competitors. Still, the rear cabin offers plenty of accoutrements, including adjustable ventilation, variable seat heaters, window shades, folding coat hooks and reading lamps.

There's plenty of room back there, too. The A8 is a bit wider than either the BMW 7 Series or Mercedes S-Class, but several inches shorter than either, which translates into slightly less legroom for the base A8. The slightly more compact Audi provides 100 cubic feet of interior volume compared with 105 in the class-leading Mercedes S-Class.

The solution for those who require limousine-like back-seat space is the A8 L model, with a five-inch longer wheelbase, producing three inches more legroom and a touch more headroom. The rear seats in the A8 L are roomy and comfortable.

The chime on the optional Acoustic Parking System ($700) warning of objects near the car when backing up can be annoying and hard to understand.

Front and rear doors open extra wide. The trunk lid opens beyond vertical to reveal a big trunk; the A8 has a larger trunk than any sedan offered by BMW, Jaguar or Mercedes-Benz.

Audi's optional navigation system doesn't offer the vivid graphical maps of other systems, but instead places the route instructions in between the speedometer and tachometer so the driver doesn't have to glance to the center of the dash. It also doesn't seem to give as many erroneous instructions as some of the other systems we've seen. The navigation system comes bundled with the acoustic parking system in the Guidance Package ($1980), and standard with the A8 L.