Audi officially announced its S8 luxury sedan today, following weeks of anticipation. The Audi S8 is equipped with a new V10 engine borrowed from the Lamborghini Gallardo. The 10-cylinder power unit develops 450 bhp of power and 540 Nm of torque from a swept volume of 5.2 litres. The torque value is achieved at as low an engine speed as 3,500 rpm. As on the Le Mans winning R8, FSI direct injection increases power output on the S8. This luxury saloon sprints from 0 to 100 km/h in 5.1 seconds, and is electronically governed at 250 km/h. It will be appearing on the market in the mid of 2006.
The driveline and chassis of the S8 have been modified to reflect the engine’s power. A quattro drivetrain of the latest generation with asymmetric/dynamic torque distribution diverts the engine’s power to all four wheels. The firmer settings of the adaptive air suspension sport and modifications to the steering ensure that the power and dynamism of the drivetrain are translated with precision into locomotion.


The 450 bhp V10 is the second generation of Audi V-engines, all with a 90-degree included angle and a spacing of 90 millimetres between cylinder centres. Key areas of the Audi version have been reengineered compared with the engine in the Lamborghini Gallardo. The bore has been increased from 82.5 to 84.5 mm; the stroke is 92.8 mm and the displacement 5204 cm3. A so-called bedplate structure – an intermediate frame – reinforces the extremely compact crankcase, which is made from cast aluminium.


 |

With its crankpin offset of 18 degrees, the V10 fires at the ideal spacing of 72 degrees crankshaft angle. A balancing shaft located within the “vee” eliminates the so-called free inertial forces of the first degree and also contributes towards the engine’s notable refinement. All four camshafts can be adjusted continuously by 42 degrees crankshaft angle, depending on load and engine speed, to optimise filling of the combustion chambers and thus enhance the power output. They are driven by no-maintenance chains and actuate the 40 valves via roller cam followers.


The V10 in the new Audi S8 uses FSI petrol direct injection. This permits a high compression ratio of 12.5:1 and a correspondingly more effective combustion process based on a lambda value of 1. The common rail injection system delivers the fuel directly to the combustion chambers in precisely metered amounts, at a pressure of up to 100 bar.


The powerful ten-cylinder engine is designed for impressive torque as well as engine power. It generates 450 bhp at 7,000 rpm, but musters up 540 Nm of torque at just 3,500 rpm. 90 percent of the torque is available from as low as 2,300 rpm. The V10 exhibits spontaneous throttle response and very refined running, and under load it also produces sonorous acoustics, as befits a dynamic car.


Driveline


A centre differential, installed longitudinally in the driveline, distributes power between the front and rear wheels according to the prevailing situation. Normally, 40 percent is routed to the front wheels and 60 percent to the rear, this slight emphasis on the rear underlining the dynamic character of the Audi S8. If the surface conditions change, the purely mechanical differential responds without any delay; it can divert up to 85 percent of power to the rear wheels, and as much as 65 percent to the front wheels. If a wheel on one axle spins, it moreover overrides the Electronic Differential Lock EDL by applying the brakes.


The new S8 is equipped with six-speed tiptronic as standard. In keeping with the character of this saloon model, the final ratio of the automatic transmission is lower than on the A8 – the saloon is still capable of forceful acceleration even in sixth gear. The electronic transmission control is optimised to change gear more dynamically. The driver can call up the transmission’s Sport mode via the selector lever – it still performs upshifts even at relatively high engine speeds. It is in addition possible to change gear manually with the shift paddles located behind the steering wheel.


Interior
The S8 adds various specific accents to this luxurious interior. This is the first time that bi-colour seats with seams in a contrasting colour have been used as standard; their four colour combinations emphasise the air of luxurious sports appeal. The colours for the seat centre sections differ from those for the side sections and head restraints. The headlining is additionally available in the S models’ signature colour silver.


Further details of the interior distinguish the sporty top model from the A8. The door sill trims are adorned with S8 emblems, and the inlays are in brushed aluminium or alternatively carbon fibre. The three-spoke leather multifunction sports steering wheel with the S emblem features colour-contrasting seams and aluminium-look shift paddles. Leather and aluminium are used on the selector lever knob. The needles on the instrument dials are in white, their scales in light grey and their values in the characteristic S italic script.
