MichaelSpoots said:
Thanks for the tip, etml. What specifically do you mean by "solvents", though? Any examples of a solvent for this purpose that I can pick up from Home Depot? I'm familiar with Goo-Gone, can you recommend any others? Thanks

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Rusty, is the Sonata's issue on the interior or exterior of the windshield?
recently I tried cleaning the interior of a windshield while humidity was high, really high, like there was water beading on the side of my toolbox high. Needless to say it wasn't fun, but I ran into the exact problem you have. I've come to the conclusion that ALL windows have this built up film, some worse than others, but we usually don't see it because the light doesn't hit it just right.
Anywho, I got the window clean and the smears gone, but it took a lot of work. I started with my usual glass cleaner, a spray wax (yeah i know, but it is the best i've used) nothing. Then glass cleaner, nothing. Another glass cleaner, nothing. Water, nothing. So i said F it, grabbed 91% isoprophyl alcohol and went to town, moderate improvement!!!!!
After 20min, about 10 rags, and spraying enough alcohol to make me light headed half of the windshield was clean. But, it was crystal clean with zero haze in 95% humidity, there wasn't a single bit of film anywhere.
So yeah, you can remove the film but it's just going to take a long time. Unless there is some magic product out there.
BTW, x2 on hating stoners. I really don't see why it is so popular, I've never had good results with it. I don't care for spray can glass cleaners, but if I were to choose one it would be Sprayway.