Manual gearbox or tiptronic: two times six gears plus quattro
At launch all S4 models will be supplied with a 6-speed manual gearbox. This latest-generation gearbox with closely spaced ratios characteristic of a sports car is noted for its extremely precise, short shifts. Thanks to a special mount for the selector forks, the gear lever is effectively protected against driveline vibrations; the driver does not feel the gear lever trembling at all.
Internal friction reduced by a series of measures increases the efficiency of the manual gearbox. This means that engine power can be converted even more efficiently into forward propulsion.
A newly developed 6-speed tiptronic transmission with Dynamic Shift Program DSP and sport program will extend the range in the second half of 2003.
This automatic transmission is designed specifically to meet demanding handling requirements: weight reduction, rapid shifts and an optimised shifting strategy make sure that the convenience of the automatic transmission is combined with the sports performance specific to the S4.
The new 6-speed transmission is 21 kilograms lighter than its predecessor; it has a total weight of just 115 kilograms. The spread of ratios has increased by 25 percent compared with a 5-speed automatic. This means a much improved accelerating performance in the low gears and a clear reduction in engine speed and consequently a reduction in both noise level and fuel consumption at high speeds. These qualities make the Audi S4 the ideal vehicle for long journeys.
The shifting speed of the new 6-speed tiptronic has been significantly optimised. The driver benefits from more spontaneous gear changes particularly when downshifting. In addition, the fact that the engine automatically double-declutches further increases agility.
Both in position D and the sport program S, the shift program responds to influencing parameters such as lateral and longitudinal acceleration and the type of accelerator pedal movement. This means that irritating upshifts when cornering, for example, can be prevented if necessary.
All Audi S models come with quattro four-wheel drive as standard. This ensures excellent traction and directional stability, and minimises the influence of the drive forces on the car's self-steering behaviour. The self-locking Torsen centre differential on the Audi S4 distributes the drive forces variably between the front and rear axles. This guarantees optimum straight-line running, high directional stability and maximum propulsion.
The lightweight aluminium suspension, based on the much-praised axle design of the A4 series, provides the ideal basis for maximum agility and, consequently, sheer driving pleasure.
Four-link front suspension and trapezoidal-link rear suspension enable maximum steering precision and clearly defined handling with excellent cornering stability. Ride comfort also benefits from this ingenious axle design because a low unsprung mass makes for a particularly sensitive response from the suspension. The wheel carriers on the new Audi S4 are made from aluminium for the same reason. Compared with a conventional steel construction this means a reduction in the unsprung mass of almost two kilograms per wheel.
This is a general characteristic for which the A4 model line has received unanimous praise in the automotive press since it first appeared, and which is accentuated even more clearly on this new model. The Audi development engineers have tuned the springs, shock absorbers and anti-roll bars even more consistently in favour of sports performance. And they have lowered the chassis - and therefore the centre of gravity - by 20 millimetres.
The new S4 generation comes as standard with one of the most elaborate and efficient rear suspension systems currently available: the self-tracking trapezoidal-link rear axle, specially designed for quattro drive. Newly tuned toe-angle kinematics optimise the directional stability and the precision of the steering response even further.
Compared with the basic version, the new S4 has a much more direct steering ratio: as far as the driver is concerned, this is a contribution to the sports-oriented handling of the agile eight-cylinder version that can be experienced in all situations. The S4 can be guided extremely precisely around all kinds of corners. A standard feature on both the saloon and the Avant is the speed-dependent servotronic which enables precise steering at high speeds as safely as effortless manoeuvring and parking.
The Audi S4 is being launched with standard-fit 8x18-inch alloy wheels produced exclusively for this vehicle. These are fitted with tyres of size 235/40 R18 which unite good road grip with direct steering properties and defined directional stability. Size 7x17 wheels, with the same Avus design that characterises the other S models, are also available with 225/45 R17 winter tyres.