Audi A6
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 Ur-S4 / Ur-S6
The 'S' prefix letter has signified Audi's sporting high-performance production models since the early 1990s. The S4 was the high-performance version of the Audi 100 saloon, and was known originally as the Audi 100 S4. It featured a 20-valve, 5-cylinder turbocharged engine and quattro permanent four-wheel drive, providing outstanding traction and roadholding in all weathers. Befitting its status at the top of the Audi 100 series, it was luxuriously appointed and featured as standard a lot of equipment that was optional on lesser models. The car was available in saloon/sedan and Avant (estate/wagon) versions.