When the new FIA Group B rule set was introduced in 1982, manufacturers chose a variety of different paths to leverage the new regulations.
Audi's path was slightly different from those at the front of the pack - Lancia and Peugeot. Most factories produced race versions of their cars that were not just modified from the homologation versions offered to the public, but were barely common in any way. That's where Audi was a little different. It kept with a philosophy of building it's rally cars on very similar principles to its road going equivalents.
When the S1 variant of the Audi Sport Quattro was introduced for the 1984 season, it was much the same basic configuration of the street-going version, with the engine in a position very forward of the front axle line. The Sport Quattro was Audi’s first real Group B car.