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 original B5 Audi RS4 Avant quattro ("Typ" 8D) was introduced by Audi in late 1999, for main production and sale from 2000, as the successor to the Porsche / quattro GmbH joint venture-developed Audi RS2 Avant. The vehicle, like its RS2 predecessor, was available only as an Avant and was built on an existing platform, in this case the Volkswagen Group B5 platform shared with the A4 and S4. Retail price was around DM 103,584. The RS 4 was available for sale in most of Europe, parts of Asia and in some Latin American countries.