Chicago Pronunciation

In all the years that I've lived in Chicago, it always seemed to me that Chicagoans couldn't pronounce German names correctly. Every cab driver seemed to call Goethe St. something that sounded like "Go easy" with a th instead of an s.

However, riding on a northbound #22 bus yesterday, I heard the automated announcement for Geothe St., and it sounded very much like how Goethe would have pronounced it himself.

Now I wonder what a Mozart St. announcement sounds like. Do they pronounce the z as a "tz" sound, as in the German, or just as a z (which is how I've always heard it)?