I think, the photo of the puzzle car must have been taken in the courtyard of Gottlob Auwärter senior's company, situated in Kaltentalerstraße 9, Stuttgart-Möhringen. Same workshop gates pictured at the attached photo.
The attached photo describes, that from 1937 on, coachwork had to be built up outside the workshop of the Auwärter OHG (Ernst und Paul Auwärter), because the interior was too small for it