Have you tried the Geogen German surname mapping site?
There are lots of surname mapping sites out there, but this is the only one I know of that focusses exclusively on Germany and Austria.
Geogen is brainchild of Christoph Stöpel, a software developer from Ludwigsfelde, Germany.
About Geogen, Stöpel writes:
“Geogen is the short form for ‘geographical genealogy’ which means location-based ancestor research. On this website you can create maps which show the distribution of surnames in Germany and Austria. Significant concentrations can point to a local root of the family or of the family name.”
It’s best to search in German. Stöpel advises: “Enter your surname in the upper input field and click the »Research« button. German special characters (ä, ö, ü and ß) are distinct letters. This means you must look for Mueller and Müller in separate searches.”
Questions? You can contact Stöpel at firstname.lastname@example.org.
Happy searching on the Geogen German surname mapping site.