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 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..