Feels like reading an oil thread.
My passenger side mirror dips in reverse when the selection switch is in the left position. My salesman showed me that feature on the day I picked up the car in February, 2011.
At some point in the past, I used a BMW Vin Decoder website (don't remember which one) and got a full listing of all features on my 2011 135i. In the list of options on my car was this line item:
S430A Interior/outside mirror with auto dip
This was not grouped under any particular heading. All I have is a complete set of options, and this was one of the items listed.
I cannot find any reference to an exterior auto dip mirror in the 2011 sales booklet, but I do see lots of references to outside power mirrors with memory presets when the car is equipped with power seats or the Premium Package, which mine has. I feel like there might be a relationship to one of those options.
My car does not have Comfort Access.
Hope this helps someone.
Peace... Mack