In late 1997, the introduction of a new A6, based on a new design automobile platform - the Volkswagen Group C5 platform, with a new range of internal combustion engines was announced. The Italian-redesigned body presented a modern design, with a fastback styling which set the trend for the Audi lineup, and gave the relatively large saloon an aerodynamic shell with a low coefficient of drag of 0.28.
As a result of complying with FMVSS, the North American models were equipped with front and rear bumpers that protruded several inches further than their European counterparts, with modified brackets and bumper suspension assemblies as result, and child-seat tethers for occupant safety.
North American C5 A6 models received the 2.8 litre, 30-valve V6 engine, the 2.7 litre "biturbo" V6 and the 4.2 litre 40-valve V8 petrol engines. The V8 models arrived with significantly altered exterior body panels, with slightly more flared wheel arches (fenders), revised headlamps and grille design, larger roadwheels (8Jx17"), larger brakes and Torsen-based quattro permanent four-wheel drive as standard.
Source: Wikipedia, 2011