My girlfriend's car is possessed. Everytime I drive it, there is a weird film on the windshield and windows. I clean them and in a week or so, it's back. It is not smoked in and is kept clean and hardly driven. Sometimes it will be shut up for days. The car has a waxy scented candle smell... like one of those tarts people burn. It smells like a burnt tart... vanilla/coffee/cinnamony odor. I can't seem to find the cause. She said a tart did melt in there a long time ago but it's gone. Could the summer heat be reigniting the oils and causing some sort of vapor to form on the windows? I mean, this car is clean and free of any obvious causes. But the car always has smelled like that. That was the first thing I noticed about it and that was years ago and in the winter so there goes the heat idea.