Bergia is what I was looking for indeed. I think I can call this puzzle solved now. After reading the online source it appears that Lammerse was right, the factory was in Wehl. After they stopped production the machines went to the companies "Bergia" and "Reform" in nearby Zeddam.
However, it would be nice to find out more:
Was Mr. Ley connected to the German make with the same name?
Was there a relation with the D.K.W. vehicle it very closely resembles?
How was it powered?