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 S5
Fitted with a completely new and more powerful 3-litre V6 petrol engine, the S5 has direct injection as well as a twin-scroll turbocharger to reduce both weight, and cost. The turbocharger is mounted within the engine V and as a result has reduced turbo lag response times. The quattro all-wheel drive system receives power through a locking centre differential that splits torque sent to the wheels at 40% to the front and 60% to the rear. The system can also divert up to 70% to the front or up to 85% to the rear. time is around 4.4 seconds (coupé) & 4.5 seconds (sportback), with a limited top speed of .