First Look: Audi's New Super Sedan

Following are the remarks of Stephan Reil, Technical Director of quattro GmbH, about Audi's new super sedan, the RS 6.

0 to 62 mph in 4.7 sec.
0 to 125 mph in 17.6 sec.
45 to 70 mph in 3.1 sec.
70 to 105 mph in 6.7 sec.

As you can see, performance typical of a sports car from a five-seater saloon, with a power-to-weight ratio of just 9 lb per horsepower. The result is superior flexibility and accelerating ability.

So how does it achieve this outstanding performance? Much of the answer is to be found inside the engine compartment. Let me begin, then, with the very nerve center of our RS 6, the V8 biturbo engine.

The 4.2-liter, 340-bhp V8 engine from the Audi S6 is the basis. Through the incorporation of two turbochargers and other accompanying measures, we have significantly boosted its torque and power output on the RS 6. But the beefy way it builds up torque and power, typical of a turbo engine, was something we were particularly keen to achieve. The engine produces 413 lb-ft (560 Nm) of torque at only 1950 rpm and maintains this level constantly all the way up to 5600 rpm.

And as on the RS 4 before it, the biturbo engine not only has ample torque across a broad engine speed range, but also an exceptionally broad output plateau even for a sports car. This means that the peak output of 450 bhp is achieved at only 5700 rpm and is maintained at this high level right up to 6400 rpm.

We managed to achieve such performance values, first of all, because of Audi's longstanding expertise in the field of turbo engines. As far back as 1994, the RS2 Avant was summoning up 315 bhp with its five-cylinder, 20-valve turbo engine. Even then, it was demonstrating impressively how performance worthy of a sports car could be achieved by means of turbo technology in an Avant model that was as practical as it was attractive.

We still vividly recollect the immense power output and the capacity to thrill of our first high-performance sports car. The RS 4, a 380-bhp V6 biturbo engine, and a massive peak torque of 325 lb-ft (440 Nm) right across an extremely broad speed range from 2500 to 6000 rpm.

We were also able to make very specific use of this expertise in turbo technology when developing the RS 6's engine. In addition to integrating and applying the two turbochargers, we redesigned and exhaustively tested all components subjected to high loads such as the engine block, crankshaft, connecting rods, pistons, etc. in order to satisfy our exacting standards and quality requirements with regard to durability.

This comprehensive overhaul covered virtually all areas of the eight-cylinder aluminum engine with a 90-degree vee. Here are just some of the measures implemented:

* A completely newly developed cylinder head with enlarged water jacket
* Completely new dual-branch cold-air admission with central dual-chamber air cleaner in the engine's vee
* Separate air routing to the compressors
* Two hot-film air mass sensors
* Pressure-loss optimized charge air cooler
* Two KO4 turbochargers with a maximum boost pressure of 0.8 bar
* New, back-pressure-optimized dual-branch exhaust system, with two metal-base primary and main catalytic converters in each branch
* Motronic ME 7.1.1 with boost-pressure and exhaust-gas temperature control

The compression ratio is exceptionally high for a turbo engine at 9.8:1. In addition to improved responsiveness from high torque even at low engine speeds, this also benefits fuel consumption at part load.

The RS 6, of course, has quattro permanent four-wheel drive. It transforms its power into propulsion via a 5-speed tiptronic automatic transmission and all four wheels. The overtly sporty 18-in. suspension with the innovative DRC damper system and a brake system that befits its high performance are further features that ensure maximum traction and optimum handling.

The five-speed tiptronic, with its enlarged transmission flange, has been adopted from the A8 12-cylinder. The short shifting times and the additional Sport position in the transmission gate produce spontaneous agility in every driving situation. The standard, ergonomically advantageous paddles mounted on the steering wheel provide scope for direct manipulation of gearshifts manually. Thanks to the TIP-IN function, it is not even necessary to push the selector lever into the tiptronic gate first.

The left-hand paddle is for downshifts, and the right-hand one is for selecting the next gear up. A new feature that is specific to the RS 6 is an overriding logic that retains the individual transmission speeds at higher than their customary engine speeds if lateral acceleration exceeds specified threshold values.

The suspension of the RS 6, with the new DRC damper system, is a special technical highlight. It is based on the sporty aluminum suspension of the S6, but the spring rate has been increased by 30% and it is a further 10mm lower. The ingenious Dynamic Ride Control is an automatic pitch and roll compensation system. It is based on purely mechanical-hydraulic processes and works entirely without the use of electronics. It merely uses flows of fluid that are generated when the suspension is compressed.

Each of the front single-tube dampers is connected to the diagonally opposed rear damper via a central valve. In a given driving situation, fluid movements are induced in the lines. These activate additional damping forces via the throttles integrated into the two central valves and a nitrogen-charged compensation volume.

The operating principle of the central valves is as follows: When the brakes are applied, the vehicle will pitch. The front suspension is compressed, and the rear suspension extended. The fluid flows from the front to the rear dampers. The initial damping effect of the compression stage at the front and of the rebound stage at the rear is at its maximum. This is evident from the sharp rise in the characteristic. The pitching movement is efficiently reduced.

The system behaves in precisely the same way when the steering is turned, for instance on a right-hand bend. In this case, however, the fluid flows diagonally from the left-hand dampers on the outside wheels to the inside wheels. The fluid has to flow through the restrictor, and both left-hand dampers attain maximum firmness in the compression stage. The rolling movement is efficiently reduced.

If they are compressed simultaneously on both sides, the plunger in the central valve is forced upwards and the conventional damping effect of the single-tube dampers is obtained. With this broad spread of damping characteristics, the DRC assures exceptionally good ride comfort, coupled with excellent resistance to rolling and pitching.

Thanks to the continuous, swift, situation-based way in which the highly responsive DRC damper system varies the damping force, it produces maneuverability, precision steering reactions and neutral self-steering characteristics even at elevated cornering speeds.

The large 8.5x18-in. cast-aluminum wheels of nine-spoke design are fitted with 255/40R-18 low-section tires. Every RS 6 comes with tire pressure monitoring as standard. The large wheels mean that there is the necessary space for the 18-in. high-performance brake system, which achieves an average deceleration of 10.7 m/s2 or, put another way, brings the RS 6 from 62 mph to 0 in 2.6 seconds.

At the front there are 8-piston fixed-caliper and single-piston floating-caliper brakes at the rear. It has ventilated brake discs in front and rear. As on the RS4, the cast friction ring is connected to the aluminum brake-disc chamber by means of 14 steel pins. This composite technology, used in the world of motorsport, improves the brake disc's service life as a result of its "floating" arrangement, particularly when exposed to high loads and disc temperatures. The weight reduction is a further advantage.

The RS 6 is equipped as standard with the new ESP 5.7 Electronic Stability Program with integral brake assist. It has been specially matched to the requirements of the sporty RS 6. Greater angles of attitude are deliberately allowed, to maximize its dynamic behavior. Any intervention by the system occurs late on and is brief, as befits a typical sports car.

The design of the two RS 6 body versions is a clear statement: It marks a clear commitment to potential and performance, without resorting to a plethora of distinguishing features. The subtle signs by which the RS 6 can be identified are more a case of pointers that are designed to appeal to true connoisseurs and enthusiasts.

In keeping with the principle of "form follows function," there are for instance three large rhombus-pattern air apertures for cooling the water, oil and charge air, which dominate the deep front apron. Two vertical flaps on the inner flanks of the air intake apertures at the sides improve the air routing to the charge air coolers. The aerodynamically shaped spoiler lip also contributes to this effect, as well as boosting the negative lift at the front axle.

The rear apron echoes the design principle of the front end with its three small, visually identical grille inserts. Oval tailpipes on the right and left provide a highlight in gleaming chrome. For additional negative lift, there is a spoiler on the luggage compartment lid of the RS 6. The sporty design of the sides, with integral sills, accentuates the impression of power.

All design-frames and the door mirrors are in matte aluminum. Like the RS 6 logo, with its laser red rhombus on the rear lid, radiator grille and door sill trims, they are some of the subtle exterior distinguishing features.

The maximum daily production output of this high-performance vehicle is 20 units. It is being manufactured by quattro GmbH in conjunction with Audi's Neckarsulm plant. In eight cycles each taking 25 minutes, the vehicle proceeds through final assembly on a purpose-built, flexible assembly line, where assembly and finishing tasks are performed by hand. We likewise oversee the concluding quality check, involving 16 test cycles which include a 100-percent road test.