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
Apparently there is also a myth that you can beat a speed camera by driving at the correct legal speed. Noone has ever had the idea to put this to the test, though.
Until last Monday nothing. Then we went to the car-wash and asked for "The works" which included a cardboard rose air freshener which we hung from the rear view mirror. It doesn't really smell of anything and it will be binned before long.
I had a wasp buzzing round my mirror on the way to work this morning. Went to swat it, missed, caught the bluetooth clipped to my sun visor knocking it off, tried to catch it and knocked the main beams on, dazzling a copper. Took some explaining and a mandatory breath test
I go with nothing. Too much of a distraction, plus, anything obstructing your view out of a windscreen could just be enough to hide a pedestrian, cyclist, or motorcyclist. So, hang your air fresheners from the roof mounted rear passenger grab handle instead, on the side behind the driver.