Audi S6
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 V8
At the initial launch of the Audi V8, the only offering was the 3.6-litre powerplant, which displaced . This V8 engine was DIN-rated with a maximum motive power output of at 5,800 revolutions per minute (rpm), and generated a torque turning force of at 4,000 rpm. In August 1991, Audi introduced a 4.2-litre engine, displacing , to complement the choice of the existing 3.6-litre V8. This shared many components from the 3.6 V8, and the 4.2 unit was identical to the optional V8 used in the Audi S4 (aka "Ur-S4"), sharing the same rated outputs and ABH identification code. Like the 3.6 V8 model, the existing four-speed automatic gearbox remained available. However, a new six-speed manual gearbox replaced the five-speed manual. This powerplant is identified by chrome 'V8' badges on the front grille and at trunk lid, where in some cars also '4.2 quattro' badge is present.