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 RS 4
The Audi B7 RS4 was the only "RS" Audi powered by a naturally aspirated engine until the Audi RS5 was presented at the 2010 Geneva Motor Show. The RS5 also uses a 4.2 litre high revving V8. The RS5 also dropped the Getrag 6-speed manual in favour of a 7-speed "S tronic" dual clutch semi-automatic.