Phew, we got there in the end! Well done Guido, and almost but not quite Autogids!
I must confess that I didn't know about this Mazda until fairly recently. Seems it was produced from c.1971 until 1982, so strange that it remained so secret after 11 years in production. If any other puzzlers can add any more information, please feel free. Thanks.
P.S. Guido, you're getting dangerously close to become a Pro!