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
Fitted with a completely new and more powerful 3-litre V6 petrol engine, the S5 has direct injection as well as a twin-scroll turbocharger to reduce both weight, and cost. The turbocharger is mounted within the engine V and as a result has reduced turbo lag response times. The quattro all-wheel drive system receives power through a locking centre differential that splits torque sent to the wheels at 40% to the front and 60% to the rear. The system can also divert up to 70% to the front or up to 85% to the rear. time is around 4.4 seconds (coupé) & 4.5 seconds (sportback), with a limited top speed of .