David Burgess Wise mentions a rare sports version with a six-cylinder 1960 cc engine, built from 1925 to 1926. That would fit the appearance of the puzzle car. Alas, I didn't find a name for it, so I have to guess. The displacement would make it probably a 8 Steuer-PS car, the sports version would do fine with 10 additional hp (or even 15?). How about a Heim 8/50 PS Sport?