FSI technology has impressively demonstrated its dynamic potential in motor sport - the R8 racing car equipped with it participated in the Le Mans 24 Hours five times for Audi, emerging as the winner on four of those occasions.

In the Audi S6, the FSI technology is managed by a highly advanced Bosch Motronic bearing the designation MED 9.1, operating with two separate control units according to the master/slave principle.

Unlike conventional indirect manifold injection, the FSI common rail injection system injects the fuel directly into the combustion chambers in precisely metered amounts, at a pressure of up to 100 bar. This results in an extremely homogeneous fuel/air mixture, benefiting the efficiency of the combustion process. An internal cooling effect moreover takes place, allowing the engine's basic compression ratio to be raised to a high 12.5:1. A highly efficient combustion process is the result.

The magnesium two-stage variable intake manifold is respirated via two separate air paths with two air filters. The variable intake manifold incorporates electronically controlled tumble flaps that induce a tumbling motion in the air drawn in at low engine speeds and loads; this enhances the efficiency of the combustion process inside the engine even further.

The two-stage layout of the magnesium intake manifold serves the same purpose. Depending on the load and engine speed, the longer manifold length (675 mm) is activated to provide ample torque at low and medium engine speeds, and the shorter manifold length (307 mm) to ensure high power output at higher engine speeds.

The design of the single-pipe manifolds likewise contributes to the dynamically optimised charge cycle; it is matched precisely to the firing order of the V10. On each cylinder bank, the exhaust ducting of the first and second cylinder and of the fourth and fifth cylinder is combined; it only converges with the exhaust ducting of the third cylinder relatively far down. Four main catalytic converters take charge of exhaust emission control.

The powerful ten-cylinder engine has been optimised for high torque as well as high engine power. It achieves 435 bhp (320 bhp) at 6,800 rpm, and musters up 540 Nm of torque at engine speeds as low as 3,000 to 4,000 rpm.

Over 90 percent of the torque is available from as low as 2,300 rpm. The V10 exhibits highly spontaneous throttle response and very refined running, and under load it also produces a sonorous, sportily gutsy acoustic backdrop, as befits a dynamic vehicle of Grand Touring calibre. The V10 is a far cry from a rough-diamond sports engine: for all its sporty character, this ten-cylinder engine is very low-vibration and exhibits plenty of refinement.

For Audi, lightweight design is a philosophy that has implications for every area of a vehicle. As in motor sport, the engineers developing the S6 fought to save every gram of weight possible. Thanks to its compact design and thinner walls, the V10 weighs just 220 kilograms. A dynamically balanced distribution of axle loads and impressive road behaviour are the result. For the same reason, the battery and the power management are housed in the luggage compartment.

The V10 lends the Audi S6 the road performance of a Grand Touring: the Audi S6 sprints from 0 to 100 km/h in 5.2 seconds, and the Avant estate-car version takes just one-tenth of a second longer.

The car effortlessly reaches its top speed of 250 km/h, the point at which the electronic governor smoothly cuts in, this performance being enhanced among other things by its low drag coefficient of cD 0.31.

The engine consumes a modest 13.4 litres of Super Plus fuel per 100 kilometres.

The S6 weighs 1,910 kilograms (S6 Avant: 1,970 kg), including the dynamic, sure-footed quattro permanent four-wheel drive. Every horsepower consequently has to propel just 4.39 kilograms (S6 Avant: 4.53 kg) - the power-to-weight ratio of a top-notch sports car.

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