Audi: powerful competitor; By rolling out two more vehicles in its performance S series, this German automaker is strengthening its position in the U.S. market.

You probably won't hear the chief marketing officer of an automotive company make a statement like this, but here's Scott Keogh, who holds that position at Audi of America: "There are lots of products out there and lots of very hungry competitors. And it seems that in our history here in the U.S. whenever we got the product right, the economy soured. Or when the economy was right, we did not have the complete portfolio." But, of course, the other shoe drops and Keogh is able to point out that Audi has gone from four models and four derivatives 10 years ago to today, when the company has eight models and 20 derivatives. Which makes the company more competitive with the likes of other Germany-based companies that often come to mind when thinking about German luxury marques (BMW, Porsche, Mercedes), especially as all of them have broadened their offerings to places that 10 years ago it would be hard to imagine (SUVs?). Still, Audi, which is working toward annual sales of one million worldwide, is competing by offering vehicles that have a high degree of exclusivity and performance capabilities, as is evidenced by the 2007 S6 and S8 luxury performance sedans, variants, respectively, of its A6 and A8 vehicles. Exclusivity takes the form of producing approximately 1,000 of each per year. So even though the company is working toward increasing its overall sales, it is cognizant of the fact that a good way to drive demand is by keeping some things in comparatively short supply.

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PRODUCING POWER. What's notable about both is that they are equipped with a V10 FSI (gasoline direct injection) engine, with the engine in the S8, as this is the flagship model, producing the greatest amount of horsepower, 450 hp, with the S6 being limited to 435 hp (both generate the same amount of torque: 398 lb-ft). Although this is a 10 cylinder, the unit itself is comparatively compact, measuring 26.9-in. long, 31.5-in. wide, and 28-in. high. The engine weighs just 485 lb. Apparently, some consideration had been given to an eight, but it was concluded that to do so would necessitate large, heavy pistons and con rods, which would provide high torque, but not the sporty performance that's being sought for these sedans.

The architecture of the V is a 90[degrees] included angle with 90 mm between cylinder centers. The two cylinder banks are offset by 0.73 in. The block is made from a hypereutectic aluminum alloy; low-pressure diecasting is employed. One of the benefits of the material is that the bores (which measure 3.3-in. in diameter; the stroke is 3.6 in.) don't require separate liners, even though the pistons are an aluminum alloy (the con rods are forged steel). Rather, there is a honing operation performed on the bores that exposes hard silicon crystals which obviates the need for the liner. There are four camshafts and 40 valves; the exhaust valves are sodium-filled for cooling.

The FSI system includes a common rail injector that provides fuel directly to the combustion chambers at up to 1,470 psi under the control of a Bosch MED 9.1 Motronic unit. The air is inducted via a magnesium intake manifold that has two stages, adjusted based on engine speeds and loads, with a switch from the long intake path (26.6 in.) to the short (12.1 in.) at about 4,000 rpm. When the engine is operating at low speeds and loads there are electronically controlled tumble flaps deployed to swirl the air in order to help the combustion process.

The S8 (as is the S6) is equipped with a six-speed Tiptronic transmission, which means the transmission can be treated like an ordinary automatic or can be manually shifted via either the console shift lever or steering-wheel mounted paddles. The quattro permanent four-wheel drive system is deployed. It has a longitudinally oriented self-locking center differential that distributes power fore and aft, normally 40% front and 60% rear, although if required, as much as 85% can go to the rear wheels or 65% to the front.

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LIGHT. The vehicles are built at the Audi AG plant in Neckarsulm, Germany, which also happens to be where Audi established its Aluminum Centre, or center of competence for aluminum construction, in 1994. The all-aluminum A2, which was produced from 2000-05, hailed from Neckarsulm and is an indication of the early concentration on lightweight mass production vehicles from Audi. This has led to the Audi Space Frame (ASF) design, based on all-aluminum structure and used for the A8 and, consequently the S8*. Briefly, the construction is one where there is a frame produced from extrusions and castings, such as the roof frame, side sills, seat cross members, roof posts, and floor panels. There are 29 elements used to create the frame. Joining processes for the ASF include riveting, MIG welding, and laser welding (about 65 ft, in total). Body panels are aluminum, as well. The entire body weighs in at 474 lb., so given the V10 engine and the light weight of the body, the fact that it is rated at 0 to 60 mph in 4.9 seconds is no surprise.

*The S6 has a galvanized steel body.

By Gary S. Vasilash, Editor-In-Chief

RELATED ARTICLE: "Audi"?

Although it is a German company, the work Audi isn't German. It's the translation of founder August Horch's surname into Latin. It means "listen."

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