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.
Multitronic
Multitronic was offered on front wheel drive-only versions of the Audi A4, Audi A5, Audi A6, and the SEAT Exeo with the 2.0 TSI gasoline engine. It is not compatible with the quattro four-wheel drive system, nor transverse engine installations such as in the Audi A3. At first, the torque limit was , but the transmission is now modified to withstand torque. In 2014 Audi announced to discontinue Multitronic and replace it with S tronic, effectively making the Audi A5 8T the last model it was sold with.