<center><img src="http://i7.photobucket.com/albums/y261/laanilta/Donau_badge.jpg"></center><p>Picture was taken from a junkyard in Finland. Seems to be the only photo of this car, assuming that it is a car. I understand Donau refers to both the Danube and a classic rally/get-together hosted in Germany. Any relation to Auto Union/Audi?

As Saxony was a part of the GDR after the war, the prewar designs for Auto Union's cars were taken by the east and produced in a number of places. As near as I can tell the Donau is a DKW made in Yugoslavia. The eastern versions of the DKWs (most notably made by IFA) were powered by 2-cylinder 2-strokes as the 3-cylinder had not reached production when the war broke out.
Cheers!