Hermann Schild? No
Won a race trying to be a GT? Yes
Still alive? No
or Georg Umbenhauer? He won the three-week version, but though he was based out of Bavaria I was fooled by the only post-war result I could find for him being in the SBZ.
Well I have to blame momentarily ignorance here, cause of course Erfurt a part of the SBZ. Georg Umbenhauer is the correct answer.