March 2, 2000

Audi S4 and S4 Avant

The equipment and data stated here refer to the model range offered for sale in Germany. We reserve the right to make changes. Errors and omissions excepted.

The sporting and elegant Audi S4 effortlessly makes its mark. A glance at the performance figures for the new 2.7-litre V6 biturbo engine with its two small turbochargers that cut in smoothly when needed is enough to show what a superior impression the S4 is capable of making. This power unit, with five valves per cylinder, delivers its maximum output of 195 kW (265 bhp) at just 5800 rpm. The shape of the torque curve expresses its supreme character even more clearly. 400 Nm of torque are available over a broad engine-speed range from 1850 to 3600 rpm.

Using smaller turbochargers but fitting one to each bank of cylinders has clear advantages on the V6 engine. The more rapid response of the smaller turbines leads to the desired high torque even at low engine speeds. Thanks to their lower inertia, the engine responds more readily to rapid pressure on the accelerator. The short distances between the cylinder exhaust ports and the turbocharger inlets mean that the exhaust gas loses less momentum and charging efficiency is thus increased.

Each bank of cylinders has an intercooler which reduces the temperature of the intake air. Efficient cooling of the charge air is crucial to the forced aspiration principle: the cooler the air, the higher its density and the more oxygen is available for combustion. With cooled air, therefore, it is possible to achieve even higher engine efficiency.

The special shape of the inlet ports, which creates a tumbling motion in the mixture charge as it enters the combustion chamber, also helps to make combustion cleaner and more efficient. The optimum swirl imparted to the fuel-air mixture by this tumble effect improves the combustion process and thus has a positive effect on engine efficiency.

The intake camshafts for the two five-valve cylinder heads are hydraulically adjustable to optimise the torque curve. These adjustments to the valve timing increase torque by about ten percent in the low and medium engine-speed ranges.

The bare figures for the S4 and S4 Avant translate into impressive performance: the saloon takes just 5.7 seconds to accelerate from 0 to 100 km/h, and there may just be enough time to blink before the S4 Avant gets there too - 0.1 of a second later to be precise. In both cases, top speed is governed to 250 km/h.

Consumption figures of 11.3 and 11.4 litres per 100 km respectively (93/116/EC overall consumption, saloon and Avant) illustrate just how efficient the engine is. Exhaust-gas temperature control, employed here for the first time, leads to more efficient use of the fuel and lower emissions. Fitted with the latest-generation electronic engine management system, this power unit meets the strict requirements of the D3 emission standard in full.

The power of the V6 twin turbo is converted reliably and effectively into traction by the 6-speed sports-ratio gearbox and permanent four-wheel drive. The S4's aluminium suspension has a noticeably positive effect on handling. In addition to all control arms in the four-link front and double-wishbone rear suspension, all pivot bearings are now made of aluminium as well.

The brake system has also been upgraded to match this surging forward thrust: large ventilated disc brakes front and rear with aluminium brake calipers ensure optimum braking performance.

On the Audi S4, the anti-lock brake system (ABS) and electronic brake-force distribution system (EBD) are under the overall control of the electronic stability program (ESP). This makes both the saloon and the estate version two of the safest high-performance cars on the road.

On the outside, the differences between the S4 and the basic A4 amount to no more than a few functionally-based design features. The new model's powerful appearance is of course also partly due to its sports suspension, with wide 225 tyres and 17-inch "Avus" alloy wheels.

Large air intakes give a more emphatic look to the front end of the car. The headlights with their xenon dipped beams and clear glass covers also contribute to the sporty appearance. The car is equipped with automatic headlight range control and high-pressure headlight cleaning jets.

Inside, the S4 and S4 Avant have remained true to the restrained style so typical of Audi's S models. High-quality Jacquard satin seat covers and door trims in either Onyx or Platinum are standard. There is a choice of carbon or aluminium with diamond silver finish for the trim strips on the dashboard and doors, an additional option in the form of walnut is available at an extra charge. Those who like a little extra luxury can choose between elegant silk nappa leather in Onyx, Platinum or Silver or a combination of blue Alcantara and onyx-coloured leather.

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