Does window tint make a vehicle hotter?

Answer 1

Yes, it can,

If your window tint reflects IR heat it can be warmer in the car when the temperatures are cooler outside. because the heat is reflected back into the car.

As for sitting in the hot summer sun the tinted windows will feel cooler inside than the non-tinted windows.

My car with 35% VLT Film that was a high quality ceramic film that blocked 90% or more of the IR. When I was driving in the summer with the sun coming in between the side window and the windshield on my leg, my calf was much cooler where the sun was shielded by the tinted window, my lower part of the leg was much warmer.