I have a 2004. Sorry, can't change the title. My side mirror looks to be auto dimming in addition heated. It has provisions for heater, and also another connector that I think is auto dimming. There is dark fluid behind the mirror.
Was looking for a replacement mirror and they all indicate for 2005 models, and the connector is definitely different. Anyone familiar with this problem?

 

Think I answered my own question. Part number is: 51-16-7-116-747

Many after market vendors show this didn't exist on a 2004 E60 545i, but mine is breathing proof that it did.

 

Glad you found it. Sometimes options change late in the model year depending on what month your build took place.