Touring cars

In 1990, having completed their objective to market cars in the United States, Audi returned to Europe, turning first to the Deutsche Tourenwagen Meisterschaft (DTM) series with the Audi V8, then in 1993, being unwilling to build cars for the new formula, they turned their attention to the fast growing Supertouring series, which took place nationally, first in the French Supertourisme and Italian Superturismo. In the following year, Audi would switch to the German Super Tourenwagen (known as STW) and then to British Touring Car Championship (BTCC) the year after that.

The Fédération Internationale de l'Automobile (FIA), having difficulty regulating the quattro four wheel drive system, and the impact it had on the competitors, would eventually ban all four wheel drive cars from competing in 1998, by then Audi switched all their works efforts to sports car racing.

By 2000, Audi would still compete in the US with their RS4 for the SCCA Speed World GT Challenge, through dealer/team Champion Racing competing against Corvettes, Vipers, and smaller BMWs (where it is one of the few series to permit 4WD cars). In 2003, Champion Racing entered an RS6. Once again, the quattro four wheel drive was superior and Champion Audi won the championship. They returned in 2004 to defend their title but a newcomer, Cadillac with the new Omega Chassis CTS-V, gave them a run for their money. After four victories in a row, the Audis were sanctioned with several negative changes that deeply affected the car's performance. Namely, added ballasts and Champion Audi deciding to go with different tires and backing off the turbos boost pressure.

In 2004, after years of competing with the TT-R in the revitalized DTM series, with privateer team Abt Racing/Christian Abt taking the 2002 title with Laurent Aïello, Audi returned as a full factory effort to touring car racing by entering two factory supported Joest Racing Audi A4s.