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 A6
Upon introducing the C4 series A6, Audi made small revisions to what was previously known as the Audi S4, renaming it the Audi S6; the S4 name would eventually be re-used for a completely different model derived from Audi's smaller Volkswagen Group B platform-based Audi A4. As this was the first S6 model from Audi, it is commonly referred to as the "Ur-S6", derived from the German augmentive, "Ursprünglich" (meaning: original). It was available as both a saloon/sedan ("typ" 4A5), and an "Avant" ("typ" 4A9) (estate/wagon) to European and United States customers, but only as a saloon in Canada, Asia and Australia.