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 A4
Torsen T-2 based quattro permanent four-wheel drive remained as an option on most A4 models. Audi retired its 5-speed manual transmissions in favour of a new Getrag 6-speed. As before, multitronic continuously variable transmission (CVT), now with selectable 'seven-speeds', was an option on front-wheel drive models, whilst a conventional ZF 6HP 6-speed tiptronic automatic transmission was an option on the quattro four-wheel drive models.