Where are your sunglasses? That is the million dollar question. If they are not on your head then who know where they are. One of our favorite places is where we can see them. That way we know we did not forget them as we leave the car and we can see we have them when hung back up as we return to the car.
When you hang your sunglasses it prevents any type of contact with the lenses which prevents them from being scratched. Try it on the sun visor or any handle ( any non-door handle).