Original: Audi's mid-size car was previously named the Audi 100 (or Audi 5000 in the United States), and was released in three successive generations (Audi C1, Audi C2 and Audi C3). In 1994, the latest generation (C4) of the Audi 100 was facelifted and re-badged as the Audi A6, to fit in with Audi's new alphanumeric nomenclature (as the full-size A8 had just been introduced).
Simplified: The Audi A6 is a automobile produced by Audi.