Does anyone know what these lines are on the perimeter of my driver's side view mirror? There aren't any on my passenger side, only the driver's. Thanks!

 

Auto dim feature?

 

Differential rust. These threads get more interesting everyday!

 

Thats the outline of the autodim portion if the mirror.

 

Bingo!

 

So the passenger's side doesn't auto dim?

 

Nope, therr is no need. It all has to do with reflections.

 

 

Anybody have a decent explanation as to how autodim works?

 

When exposed to headlights from behind, the auto-dim mirror looks kinda like a tinted window and cuts the glare / reflection. Probably just a coating / film on the glass but it's awesome!
Just go drive around at night in traffic and look at the difference between your driver side & rear-view mirror compared to the passenger side.