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 A8
Audi introduced the S8 4.2 quattro into the European market in 1996. The S8 followed the naming convention of other high-performance Audi "S" models such as the Audi A6-derived S6 and was similar in vein of Mercedes-Benz AMG models. In markets such as the UK, the S8 was only available with the automatic transmission. Cosmetically, Audi differentiated the S8 from the A8 with solid aluminium alloy door mirror housings, chrome-effect beltline and lower front grille trim, and polished twin exhaust pipes, along with subtle "S8" badging. 14-way power adjustable and heated sports front seats with memory function were fitted as were heated rear seats. Standard alloy wheels were 18-inch cast aluminium alloy "Avus" six-spoke style. After the 1999 facelift, 20-inch polished nine-spoke RS wheels became an option. In 2002, 18-inch nine-spoke RS wheels became a no-cost option.