but I only have documentation for W210 cars. I think that rather than powering the movement of the outside mirrors, your fuse #21 supplies current for the heated function of them. With ignition off, can you measure the current drain from the battery and then pull fuse #21 without turning on the ignition. It would be good to know if the drain changes. As far as the heated windshield fluid goes, I think that the car may circulate coolant thru the reservoir and that there is some kind of thermo switch that is involved with this. My guess would be that the electrical coolant pump that supports the REST function on HVAC system is also fed by fuse #21.