Audi A6
Audi made a high-performance, 4.2-litre V8 engine (parts code prefix: 077, identification code: AEC) with a Bosch KE-Motronic ECU available as an option in the original European S4s, and made the decision to continue to do so with the S6, making a version of the 4.2 available as an optional upgrade over the 2.2-litre inline five-cylinder turbo. Unlike the five-cylinder turbocharged version, the V8-powered S6 was supplied with a four-speed automatic transmission as standard, but kept the quattro four wheel drive. A six-speed manual gearbox was also available as an option.
Audi S4
At the heart of the B8 S4 powertrain is an all-new, all aluminium-alloy 3.0-litre TFSI Supercharged (TFSI) V6 engine (parts code prefix: 06E, identification code: CAKA), and like the rest of the B8 model range, now with Fuel Stratified Injection (FSI). This petrol engine displaces , and it is rated by Audi to a power output of from 5,500 to 7,000 rpm. Torque is rated at from 2,900 to 5,300 rpm. This high power output is achieved by using forced induction – and specifically, an all-new Eaton 'Twin Vortices Series' (TVS) Roots-type positive displacement compressor. This new supercharger features twin four-lobe rotors, which are axially twisted 160 degrees. It is mounted on top of the engine, within the 'Vee', pumping air directly into the inlet manifold, and incorporates two separate water-cooled intercoolers. This new design of supercharger is said to reduce the noise, vibration, and harshness (NVH) of the engine.