The Audi Sport Quattro S1 was introduced at the end of 1984 as an update to the Audi Sport Quattro. The car featured a inline 5-cylinder engine that displaced 2,110 cc (128.8 cu in) and produced an officialy quoted figure of 350 kW / 480 PS/470 bhp). However, the turbocharger utilised a recirculating air system, with the aim of keeping the turbo spinning at high speed, and the actual figure was in excess of 500 bhp (373 kW/507 PS) at 8000 rpm. In addition to the improved power output, an aggressive aerodynamic kit was added that featured very distinctive wings and spoilers to the front and rear of the car to increase downforce. The weight was lightened to just 1,090 kg / 2,403 lb), and now accelerate from 0-100 km/h (62 mph) in just 3.1 seconds.
The S1 proved to be an immediate success in the rally circuit, helping Walter Röhrl and Christian Geistdörfer win the 1985 San Remo Rally. A modified version of the S1, was also driven by Michèle Mouton. The S1 evolution would become the final Group B car produced by Audi, with the works team withdrawing from the Championship following the 1986 rally in Portugal.
