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 S and RS models
In the past, some Audi S models competed directly with BMW M and Mercedes-AMG models, such as the B6 Audi S4 4.2 FSI versus the BMW M3 and Mercedes-Benz C32 AMG. Since 2010 however, Audi S models have been positioned more as optional engine trims. For instance the base Audi A4 (B8) engine is the 2.0 TFSI turbo four-cylinder, and with the discontinuation of the 3.2 FSI V6, that makes the Audi S4's 3.0 TFSI V6 the performance option (the B8 Audi S4 3.0 TFSI positioned closer to the E90 BMW 335i than the BMW M3). The Audi "A6" (C7) no longer has a V8 engine upgrade in the non "S" range, with the discontinuation of the C6 Audi A6 4.2 FSI that was offered from 2004 – 2011, one must go to the C7 Audi S6 4.0 TFSI..