Have this thinking that darker surface absorb more heat. There is a Mythbuster show where they demonstrated darker painted car were hotter then light color car, may be something similar. Just that an open glass window surly must allow more heat in. Requesting help with the best tint and please also advise reason its best.
Tinted window itself will get hotter than clear glass, but less infrared light (heat) reaches the interior. I don't have specific recommendation for tinting, but best wold be IR-reflective film that looks like a mirror. An open window will let the most infrared into the car, but it's more than offset by the opening allowing convective escape of warm air.
