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 100
Audi followed up the introduction of the four-door saloon in November 1968 with a two-door saloon in October 1969 and the 100 Coupé S in autumn 1970. The cars' 1.8 litre four-cylinder engines originally came in base 100 (), 100 S (), and 100 LS () versions, while the Coupé was driven by a bored-out 1.9 litre developing . From April 1970 the 100 LS could be ordered with a three-speed automatic transmission sourced from Volkswagen.