Solar energy reaching the glass arrives as visible light, ultraviolet and infrared, and the infrared portion is the part you feel as heat without seeing it. Nano-ceramic film works on that energy at the window, so less of it ends up in the cabin and on the interior surfaces. In practice that means a car that is more comfortable to get into after it has been parked, less glare in low sun and a climate system that is not fighting the heat as hard. How much difference you notice depends on the film and shade you choose, the glazing on your model and how the car is parked, so ask your installer to compare the published figures for the exact combination you are considering.