When designing the 928, which was mass-produced from model year 1978, the focus was on lightweight construction. For this reason, the doors, front wings and bonnet were all made of aluminium instead of sheet steel. Integrated into the bodyshell shape behind the plastic bumpers, there were also aluminium profiles that could withstand an impact at up to 8 km/h (5 mph) without sustaining damage.

The 928 had round headlights, which were integrated into the wings and could be raised electrically. The rounded fastback was dominated by the large window on the rear lid.

The 928 models were powered by a water-cooled V8 engine with a 90° cylinder arrangement. The engine's displacement was initially 4.5 litres and was later increased to 5.4 litres. Power was transmitted via a transaxle construction.

To improve aerodynamics, the 928 S models (mode year 1979) were given front and rear spoilers.

The rear axle on the 928 was a complete novelty. What was special about this double-wishbone suspension – also known as the Weissach axle – was its toe-in stabilizing effect. This worked more or less like a passive rear wheel steering and made a significant contribution to the active safety of the Gran Turismo.

928 (MY 1978–82)
The round rear without a spoiler was a clear identifying feature of the 928. In contrast to the later versions, this model did not yet have a front or rear spoiler. The 928's 4.5-litre engine produced 240 PS.

928 S (MY 1980–86)
The 928 S had Black front and rear spoilers, side protection strips painted in the vehicle colour, and side indicators. The displacement grew from an initial 4.7 litres to 5.0 litres (in model year 1986). The engine delivered 300 PS of power, and then 310 PS from model year 1984 and (with catalytic converter) 288 PS from model year 1986.

928 S4 (MY 1987–91)
The 928 S4 had a rounded front end with air intakes. The rear had a slope between the wide, flush-fitting rear lights and a Black rear spoiler standing up from the body. Its 5.0-litre engine produced 320 PS.