An Audi's model code can be found on the VIN sticker printed inside the front of the car's service schedule booklet. As the S2 variants did not receive a unique 2-digit identifier as part of the VIN, a six digit 'model type' code is used to differentiate the various models of the Series-4 80/90 Sedan, Avant & Coupe family.

These codes are clearly visible on the VIN sticker and can distinguish an official factory-built S2 from a clone. Obviously you cannot rely alone on seeing these model codes printed on the VIN sticker that the car is what it claims to be, but you would be mighty foolish not to check the model code on a potential S2 purchase.

The first two digits of the model code are the same as vehicle type i.e 8C for Sedan or Avant and 8B for the Coupe. The next four digits determine the engine & transmission fitted to the car and hence define model type.

8B3 025 for the 3B engined S2 Coupe (Built 09/90 - 09/92) with 5-speed gearbox

8B3 039 for the ABY engined S2 Coupe (Built 10/92 - 09/95) with 6-speed gearbox

8C2 7L9 for the ABY engined S2 Sedan (Built 02/93 - 07/94) with 6-speed gearbox

8C5 7L9 for the ABY engined S2 Avant (Built 02/93 - 07/94) with 6-speed gearbox

And finally - the RS2, which also has a unique VIN characteristic -

8C5 7K9 for the ADU engined RS2 Avant (Built 03/94 - 07/95) with 6-speed
gearbox