The heat that reaches your cabin arrives as part of the solar spectrum: visible light, ultraviolet and infrared energy. A large share of it is infrared, which you feel rather than see, and that is the part a dyed film does little about. Kepler's nano-ceramic technology is built to work across that spectrum at the glass, so solar energy is addressed before it becomes heat inside the car. In practice, Tesla owners tend to notice a cabin that is more comfortable in strong sun and less glare on bright drives, with the climate system doing less work to keep up. How much of a difference you see depends on the range and shade you choose, the glazing on your model and the conditions, so ask your dealer for the published performance data on the exact film being quoted.