4S shops do not apply film to sunroofs because the sunroof already has heat insulation and UV protection functions when it leaves the factory. Here is an introduction to automotive glass film: Reasons for not applying film to sunroofs: The sunroof itself is designed with heat insulation functionality; many sunroofs also have UV radiation protection; applying film would increase the thickness of the sunroof, potentially affecting its opening and closing, and may lead to leakage issues. The primary purpose of applying film to cars is for better heat insulation and radiation protection, which the sunroof already possesses. Functions of a sunroof: Air circulation. When driving with the sunroof open, the pressure difference between the inside and outside of the car can easily replace the stale air inside, better protecting the driver's physical and mental health; Quickly removes fog inside the car. During the rainy seasons of summer and autumn, due to high humidity, the greater the temperature difference between the inside and outside of the car, the more likely it is for fog to form on the windows, especially the windshield, obstructing the driver's view and increasing the likelihood of traffic accidents. Although most cars are now equipped with defogging devices, sometimes the effect may not be very noticeable. In such cases, if the car has a sunroof, the pressure difference between the inside and outside can be used to easily eliminate fog on the windshield; Energy saving. In the scorching summer, without a sunroof, most drivers would immediately turn on the air conditioning to lower the temperature inside the car. With a sunroof, simply opening it and utilizing the pressure difference between the inside and outside can quickly cool down the car. This method is several times faster than using air conditioning and also saves gasoline.
