The Audi 100 was a mid-sized automobile manufactured from 1968–1994.
Audi released the C4 in 1991. The C3-platform Audi V8 continued to be sold as a separate line. The major change for the C4 was the introduction of a 2.8 L, 90-degree, SOHC 12v, V6 engine. It was later joined by a 2.6 L variant, though this is actually a 60-degree engine. They are essentially the same engines offered in the 1992, B4 Audi 80. The option of quattro permanent four-wheel drive was an option across the range, and the Audi 100 quattro was available with a ZF 4-speed automatic gearbox.
Source: Wikipedia, 2011