I've just heard on the Today programme about a survey of things hanging from rear view mirrors in cars. There is apparently an urban myth that you can deflect a speed camera by having a shiny CD hanging in your front window.... here's the article about it from the DM. http://www.dailymail....1-5m-car-mirrors.html
On a point of safety Boxtops, there are plenty of places to place the Air Fresheners etc within the car! Eg/ the coat hanger that is usually above the Passenger door ( Grab Handle) & yes, the can cause a blind stop in the windscreen Area.
It's more than a hazard OG,it has been proved that having something hanging from the rear view is dangerous!
The continuous movement of the dangling rubbish is picked up by the brain and after a length of time is completely ignored by the brain, This means that the brain ignores any movement in the space that the dangly occupies so you do not see children, adults, cyclist, etc who are in that space. If you have any sense get rid of them.
Nothing - my de-odouriser is always hung there by the car-wash guys, and I always take it off immediately and transfer it to the bottom of the gear stick, out of the way.
When I first passed my test back in the '60's my mother hung a set of rosary beads on the mirror of my first car to "Protect". I don't believe in that sort of Sugar but those beads have hung in every car I've owned, but not from the mirror