Audi's mid-size car was previously named the Audi 5000, and was released in three successive generations (Audi C1, Audi C2 and Audi C3). In 1994, the latest generation (Audi C4) was facelifted and re-badged as the Audi A6. The exterior only changed slightly, new front and rear lights, new radiator grille, similarly with chassis and engine and transmission choices.
The new engines for the A6 were 1.8 litre 20v inline four cylinder, and 2.8 litre 30v V6 petrol engines, with the 2.3 litre inline five engine being dropped on most markets. For the diesel engines, an inline four 1.9 Turbocharged Direct Injection (TDI), and the inline five 2.5 TDI (103 kW (140 PS; 138 bhp)) were available.
Source: Wikipedia, 2011