I had a Regal with mildly tinted windows, tinted by a tint shop. At about 7 to 8 years old, the tint started to get air bubbles in it. When I finally got tired of the air bubbles, I took it to a tint shop and paid $50.00 and they put it under a heat lamp for a few hours and then scraped it off with what looked like a plastic scraper. {I've scraped off tint before and it was too much like work.
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That said, my daughters Altima windshield was tinted with a nearly clear tint made for rejecting heat that she swears works well. The rest of the windows were tinted at the same time, but they only used the clear stuff on the windshield. It's on my to-do list to have the clear stuff put on all of my car windows, right after I get cruise control.
It seems to me that if we could come up with a reasonable method to insulate a vehicles interior and then use a heat rejecting window film on all of the windows {if it would actually work}, increased FE would be easier to accomplish. The concept works at home.
