Audi S4
Audi's quattro four-wheel-drive system was standard on the C4 S4/S6; a first-generation Torsen-based system which used the "T-1" automatically biasing centre differential (ATB) was used on vehicles equipped with manual transmissions, while a transfer box based system was used on vehicles equipped with an automatic transmission.
Audi A4 DTM
Like all DTM racing cars, the A4 DTM resembles its A4 production equivalent only in cosmetic appearance. The A4 DTM is constructed with a carbon fiber reinforced plastic monocoque chassis and an integrated fuel tank. Powered by a Audi naturally-aspirated V8 engine, it has a power output of approximately and a maximum torque of more than . The rear-wheel drive A4 DTM also has a sequential 6-speed transmission, a 3-plate carbon fiber clutch supplied by Sandtler (2004-2010) and ZF (2011), and an adjustable multi-disc limited-slip differential.