Stermitz worked as a stewardess at Austrian Airlines and then as a model when she was elected Miss Austria in 1983.

[1][2] At the same time, she started motorsport and, supported by Helmut Marko, drove a number of races in Austria in an Alfa Romeo GTV.

[1][3] In 1987, Stermitz received a works contract with the BMW Schnitzer Team and, together with her teammate Annette Meeuvissen, competed in a BMW M3 in the 2nd division of the World Touring Car Championship.

In the same year, both started in the 500 km race in Zeltweg, which was part of the European Touring Car Championship, and also achieved seventh place there.

[1][3][4] For the 1988 season, she moved to BMW M Team Linder in the Deutsche Tourenwagen Meisterschaft (DTM) and finished in 37th place in the overall standings.