A year later the company switched to the IMSA GTO series, with its less strict rules. Only the silhouette of the Audi 90 quattro was retained: under the GTO’s carbon-fibre skin was a pure racing car. The five-cylinder engine, in its final development stage, produced 529 kW (720 bhp), and the car’s four driven wheels had 14-inch wide rims. With seven wins in 13 races, Hans Joachim Stuck took third place in the championship and the team came second in the manufacturers’ rankings.