Thanks for the lock extension, grob. You didn't say whether my interpretation of your comment ("the make is still very well known") indicates that the brand name is still in production, so I will assume that it is, unless instructed otherwise. If this is a well known German brand that is still active, the possibilities are limited to a very few. Audi and Mercedes have been eliminated, Porsche and Volkswagen are too new for the puzzle car, so I believe only BMW and Opel remain. That distinctive radiator shell doesn't look like any early BMW that I have seen, but it could be an Opel from the early 1920's. Therefore I'll try Opel from about 1922.