Audi Ur-S4 / Ur-S6
The Ur-S4 was produced from 1991 to 1994, while the Ur-S6 was produced from 1995 to 1997. They both featured a 2.2 litre, 5-cylinder engine with turbocharging and an intercooler, with of torque. In Europe, V8-powered versions of both S4 and S6 were available. The S4 version sported a engine (the same "ABH" engine as in Audi V8), the S6 had an upgraded engine "AEC" with . American versions featured a 5-speed manual transmission and in Europe a 6-speed, as well as a 4-speed automatic transmission could be substituted.
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.