Ditto...bazooka joe said:no it's not just you or living in arizona. i live in MA and it seems that it has to do with the way the air goes around the car and rolls up the back. on cool mornings i can see the exhaust come right up the back of the car...so the grime is doing the same thing. be happy you don't have to deal with all the sand and salt we get all winter long!! lookin forward to spring!!! joe