Audi 90

The Audi 90 was an upmarket version of the Audi 80. The original Audi Cabriolet was badged thus, without a number, but was closely related to the 80/90.

In Europe, the 90 name was discontinued, and all saloons were badged as 80, regardless of which engine they had. Audi of America went the opposite direction, and began selling the saloon as the 90.
Information provided by: http://en.wikipedia.org/wiki/Audi_80