Solar energy reaching your Tesla's glass arrives as visible light, ultraviolet and infrared, and the infrared part is the one you feel as heat without seeing it. Nano-ceramic film is built to work across that spectrum rather than simply darkening the glass, which is why a light shade in a strong range can outperform a dark shade in a weaker one. That also explains why visible light transmission on its own tells you very little about comfort: it describes appearance, not solar performance. When you are comparing options, look at the published figures for the exact film and shade, and ask your dealer to explain what each one means for the glazing on your car.