BMW cost cutting! My previous 335i and previous M135 had auto dim on both exterior mirrors but now my current M135 (2016) only has drivers side and interior.
Interested to see if the likes of the 5 series and above had both sides?
Evolve in Luton would be the people to speak too. They are experts in BMW tuning products and are also developing a Supra at the moment.
I have used them in the past for various BMW tunes and they are a very professional outfit.
https://www.evolveautomotive.com/makes/bmw.html