Mithras:
CGX car nut:
Leawood911:

Auto dimming essential?  Lol. 

Btw Blueflame - double negative. 

The trucks of Kansas must have regulation headlamps that never shine into your rear view mirrors.  Auto dimming mirror help immensely with that issue and add very little weight to car.  

Agreed. it's like power windows and automatic locks, something that should just be par for the course at this point. Who the hell flips a little tab on your rear-view mirror to make it darker anymore?!?

What else is nice is the gradients of dimming available so when a vehicle isn’t directly behind you, you are able to view more details, for example, is that upcoming vehicle a police car, than when you have a choice of dimmed or not with the manual version.  It makes a difference.