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 213 kilowatts version of the 4.2 available as an optional upgrade over the 2.2-litre inline five-cylinder turbo.