This video kind of surprised me:
This video from 1993 clearly shows (some) BBS wheels are produced in Japan. A bit weird for someone living next to Germany expecting a German wheel manufacturer to actually produce them in Germany!
A little research learned that the Japanese company Washibeam produces the BBS F1 Magnesium wheel and all one piece Aluminum racing wheels. They sell those wheels back to BBS Kraftfahrzeugtechnik AG and vice versa for the other wheels. In this way the production of the wheels can continue even if either BBS or Washibeam go bankrupt.