V 10, 435bhp, Luxury Sedan, Bargin Price, Black Ext, Grey Int + 19" Winter Tires on 2040-cars

The previous-generation S6 had a V-8 engine developing 340 horsepower. The twin-turbo RS 6 started life with 450 horsepower and ended up with 480. In the interim, Audi complicated things by endowing the smaller S4 with the 340-hp, 4.2-liter V-8 and the RS 4 with a direct-injection V-8 that makes 420 horsepower. The 2005 Tokyo show saw the debut of the S8, with a Lamborghini-derived V-10 and 450 horsepower.

All of this made us wonder how the new S6 would be positioned. After all, it has to upstage the S4 but stay below the S8 in the corporate pecking order. At the Detroit show in January, we found out. The S6 has the S8's 5.2-liter V-10, but with its maximum output reduced by 15 horsepower to 435. And, yes, there will be a new RS 6, which is more than a year away and promises to outgun the 500-hp BMW M5.

Audi will tell you this is all logical, that each model has a specific purpose and its own niche in the market. In the case of the S6, Audi maintains it is not just another contender in the German horsepower race. It's intended as a fast touring car rather than an out-and-out road racer and is purposely understated so it looks hardly any different from the A6.

The S6 certainly avoids the visual excess of some super-powerful sedans. There is little outward differentiation from the A6: bright vertical struts for the deep single-frame grille, flared wheel arches and rocker panels, special 19-inch wheels, and daytime running lights consisting of two rows of LEDs under the front bumper. Audi would have you know that there are 10 LEDs in total, corresponding to the engine's cylinders, although the discreet V-10 badges on the car's flanks are another reminder.

There is also nothing intimidating about driving the S6. The engine, which makes a strong, gutsy noise and should propel the car to 60 mph in 4.8 seconds, is docile when you want it to be; the six-speed Tiptronic automatic transmission works easily, whether controlled by the steering-wheel paddles or left to its own devices.

Like all Audi high-performance cars, the S6 has four-wheel drive. After years of promoting the even front-to-rear torque split of the Quattro system, Audi has given the S6 (and the S8 and latest RS 4) a 40/60 rear-biased distribution. This attempt to match the handling characteristics of its rear-drive rivals works - to a point. In a session on a tight, twisty test track, the S6 proved more agile than its predecessor but still felt front-heavy and understeered when being hustled hard; that's not surprising, really, because that's a big engine nestled between the headlights. On public roads in Germany, slick from recent rain, we were reminded, however, of the security provided by four-wheel drive in a powerful car.

The V-10 is basically a Lamborghini Gallardo powerplant that's been altered for use in a front-engine sedan. The accessories are tidier to fit in the tighter engine bay, the bore has been increased (displacement is 5.2 liters versus 5.0), and the rev range was curtailed. When installed in the S8, the V-10 makes 450 horsepower, but thanks to different intake and exhaust systems, the S6 makes do with 435.

Whereas the S8 is air-sprung, the S6 has steel springs and nonadjustable shocks. It also does without Audi's dynamic ride control, a cross-car connection of the shock absorbers to maintain body control, that was introduced with the RS 6 and is fitted to the RS 4. The S6 is uncompromisingly stiff and jolts and bounces uncomfortably over bumps. This spoils a car that is otherwise admirably suited to its role as a fast grand tourer and negates Audi's claim that the S6 is "the most refined sports sedan in its segment." Mind you, neither its segment nor its direct competitors are very clear. The Jaguar S-type R, cheaper and not quite as quick, is smoother-riding, as is the more powerful and expensive BMW M5.