I'm having an annoying problem where the inside of my windshield gets dirty with this dirty film. I leave it in the driveway most of the week where I'm not even driving it. I can't figure out what 's causing this, I have to get cleaner and wipe clean the windshield basically every few weeks!

What's causing this?

 

No clue... My FD's interior windows need to be cleaned bad!

 

I have the exact same problem... I have no idea what causes it. It almost has a slight rainbow affect after it builds up a bit so I assumed it was a film from driving with an open exhaust and the windows down.

 

+1 for this problem >_>

 

Hmm, do any of you have exhaust leaks up under the hood? Manifold?

 

nope, happens even if the car hasn't been run for a while.

 

Is it sitting out in the sun? Could be out-gassing from deteriorating vinyl or plastic I guess.

 

Well, I know this may be a long shot. This happens in my dads 626.....only when he smokes the ganja... So....yea :P (Yes I'm being serious)

 

Haha no. I suppose it could be the interiors baking, but I also use a suncover. I know the cover isn't the cause because I have the same exact one in my father's car and my other car. Don't have this film.

I wonder if it's a bad seal around the windshield? Although if there were cracks, there should be a noticable sound when driving at higher speeds like on freeways.