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 A2
The rear spoiler was reshaped, moved and extended through wind tunnel testing, and additional underbody panels were added to minimize drag to achieve a 0.25 cd figure.
The car had an automated manual transmission with a Tiptronic mode on the selector.
The car also had an ECO mode. When engaged it limited the power to (excluding kick down) and programmed the transmission to change up at the most economical point. ECO mode also activated the start/stop function, a feature that was new to European cars at the time.
In ECO mode, the clutch was disengaged when the accelerator pedal was released for maximum economy, so the car freewheels as much as possible, with the clutch re-engaging as soon as the accelerator pedal or brake pedal is touched.
The 3L also has only 4 wheel bolts and finned alloy brake drums at the rear, along with many aluminum suspension components. An internal presentation from Audi appears to indicate that the complete shell of a 3L A2 weighs around less than that of a "normal" A2. The 3L has been noted on the Autobahn under non-scientific conditions to be faster at top speed than the standard A2, mainly as a result of the extremely long 5th gear ratio and the excellent aerodynamics.