IIRC the auto dimming side mirror (on the SLK) is activated by the rear-view mirror (I seem to recall that the rear view has 2 sensors in it that compare light from behind the car to light ahead of the car)

I was removing the drivers side mirror on an slk32 and noticed the extra connecter (3 pin if memory serves)

what am I getting at?
well, if someone wanted to retrofit this to a crossfire (and already has both of the mirrors) it is do-able and I would be happy to help by supplying the mercedes connector part numbers (and the schematic if needed).

Chris