Serious question because I have no clue.

 

Winter protection against ice/snow or parking in tight spaces.

 

So you can pull into or past a narrow spot without clipping them on something,
or through a carwash.

 

These are popular in Europe where on-street parking in narrow streets means that your mirrors can get hit by a passing car coming too close. So some owners want to be able to fold their mirrors in when parking to avoid damage. Plenty of people with regular mirrors fold them in by hand when parking on busy streets. Many European cars with power fold mirrors offer the option to automatically fold them whenever the ignition is turned off, though Mini don't (except by holding down the lock button on a F56).

 

I always use them when I park anywhere other than my driveway. Better safe than sorry...

 

Folding them is pretty much a pre-requisite for parking in the City (NYC).
The other day the entire row of street-parked cars had their side mirrors destroyed by local bicyclists (stick your foot out type of vandalism, none caught).

My folded mirrors survived.

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I use them all the time when parked and especially in the city, where spaces can be tight, and when parallel parking so a stupid bicyclist doesn't clip it.

 

I have them but never use them. My car is smaller than most cars parked in the street anyway and I figure that using them calls attention to the car...which is what I don't want. The only reason I got them was for the heat in the mirrors and the washer fluid.