Factory tint
Factory tint, officially known as privacy glass, is an electrical process called "deep dipping" that involves dying the inside of automotive glass with a dark pigment. Factory tint is standard on the rear half of many new vehicles. With a common visual light transmission of 15–26%, privacy glass is installed to provide passengers and personal items privacy from outsiders, hence the name privacy glass. Since most states have a VLT legal limit of around 50% for the front driver windows and windshield, factory tint is only applied to the rear half of vehicles windows to avoid breaking the law.
Benefits
With a low VLT, the primary benefit of privacy glass is to reduce the ability to see into the vehicle, providing privacy for passengers and personal items.Heat rejection
Although privacy glass has a tint to it, its heat-rejecting properties are limited. Some manufacturers claim their privacy glass can reject a large percentage of UVA and UVB, but the infrared light is still able to pass through, allowing passengers to still feel heat from the sun. Privacy glass does prevent some heat from entering the vehicle, although not nearly as effectively as a ceramic window film.Some manufacturers, like Audi, Mercedes and Volvo Cars are now offering different types of glass in their vehicles to reduce heat from being transmitted into the cabin.