1991: performance-enhanced five-cylinder S engine with overboost control:
In the 1991 Audi S4, the Sport version of the Audi 100 (C4), a turbocharged 2.2-liter 20-valve five-cylinder inline engine is at work. It develops 169 kW (230 hp) at 5,900 rpm. Thanks to a brief increase in boost pressure, a peak torque of 350 newton meters (258.15) is achieved at 1,950 revolutions per minute. The engine also powers the Audi S2 Avant (B4) and the Audi S2 Coupé (B3). In 1994, the Audi S4 becomes known as the Audi S6.