I see a lot of confusion here. Drivers of an advance energy vehicle struggling with heat energy. Let me explain some basics and you can go crazy with the details.
Roughly 49 percent of solar heat is in visible light. Same for IR, 2% is in uv. Not numbers you will see on the internet, but roll with it, I know people who actually measured it (now eastmann performance films).
Anyway, assuming you have chosen a film that is not microwave safe, which is to say not a regular film made of ink, then your film absorbs IR to some degree and would be considered a heat control film to some degree. It doesnt matter to me how much, this is basic info and you can scrap amongst yourselves as to which is the best product, but for the love of God get over 1 % differences as you could not feel it.
Anyway, things that absorb heat get hot. And that heat seeks the lower energy state of cooler atoms in the same way water seeks to level itself if offered an opportunity. High energy flows to low energy to get equilibrium, this is a pesky rule of physics. Your car is 160-to 180f sitting in hot sun. While the film stops the sun, it also absorbs the heat from inside the greenhouse of your car and lets that now hot glass have a better emIssion of heat to the cooler 90 degree outside enviroment. When you drive, like a radiator on a gas engine car, the wind is a energy deficit hole that also allows for energy to leave the greenhouse. The glass is reflective and the ceramic or other material in a heat tint allows absorbtion of heat, rather than reflection, so the glass becomes a part of the conduit of emitted heat from the inside of the car.
I say all this because everybody focuses on the sun, but the heat is inside the car.
In the winter, the fil also absorbs heat, warming the window glass. 20 degress more than abiant is pretty common. Same rules apply though, heat flows to the cold area.
