Thanks, Time Lord!

Please sign me up for at least one, possibly two, of your new improved fan regulators.

No surprise to me that BMW and Mercedes (and Porsche, and VW) use common components. Nearly all parts like this are purchased from first tier suppliers who not only manufacture, but also do the detail design and development of similar electronic components. Forty years ago some of the biggest car makers (Ford, where I was then) would make some parts like this themselves, or possibly control the internal details on their drawings or specs, but that has evolved to the more efficient practice of just specifying functional requirements.

Thanks for your explorations!