I just answer from Andreas: there were commercials of the Audi 80 Avant, but unfortunately he don't own one.
There wans't any bigger film about the introducing the model to the Audi-dealers, made by Audi. For several other cars were made them, but not for the B4 Avant.

By the way: Andreas Bauditz want to become a imcdb-member, too. He want to show a lot of scenes with Audi 100's