I haven't been able to verify my information, so I think the websites (both!) where I got it from are incorrect.
Therefore I believe the car to be what you say it is, an Adler Trumpf Streamliner from 1937, and in fact this particular model hasn't featured on Auto Puzzles before, so you have a point and the puzzle is solved!
It was therefore much easier than I thought, and pnegyesi was right!