Yet the A8 remains fresh. Its clean, elegant profile emphasizes its large wheel arches and massive aluminum wheels. Audi has mastered the art of designing sedans that are striking, even imposing, without being overbearing. Available 17- and even 18-inch wheels (the latter are standard on S8) add to the big Audi's aggressive but understated appearance. The low, hunkered-down stance of the S8 gives it an aura of high-speed Autobahn capability.

Underneath the A8's aluminum body is the Audi Space Frame. Developed with Alcoa, this patented structure comprises seven different aluminum alloys. It has fewer parts (and therefore joints) than the typical steel unit-body. It's more rigid, and 40 percent lighter than a steel frame. Even with Audi's all-wheel drive system, the A8 weighs substantially less than the Mercedes-Benz S430 or even the new BMW 745i.

Furthermore, aluminum's superior energy-absorbing capabilities helped the A8 to earn the National Highway Traffic Safety Administration's dual five-star safety rating. It might surprise some people to know that it was the only premium luxury sedan to protect its passengers so well.

A8 was the first automobile with dual front airbags and side-protection airbags for both front and rear passengers. The current model adds Sideguard bags that discharge from the roof lining and help cover the side window area.

At 310 horsepower, the A8's 4.2-liter V8 sandwiches between the Mercedes-Benz S430 and the more powerful BMW 745i. Yet, thanks to the engine's efficiency, and the Audi's lighter weight, the A8 escapes the indignity of a gas-guzzler tax on its window sticker.