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 S5
The Audi S5 is the high-performance variant of Audi's A5. It is also the coupé, cabriolet, and five-door fastback versions of the fourth-generation (B8) Audi S4 saloon and estate models.