Now that the cool-paint idea is gone from California’s cool-car proposal, there remains just a requirement for solar-reflective glass. At least they’re now on a solid technical footing. According to language proposed but not yet adopted as I write this, starting in 2012, all vehicles up to 10,000 pounds must have windshields that reflect at least 30 percent of solar energy, side glass and backlights that exclude at least 42 percent, and sunroofs (if so equipped) that bar at least 65 percent.
Requiring such high-performance glass as standard equipment is a radical idea, not that the technology doesn’t exist, but the cars that have it now tend to be very expensive; think BMW and Mercedes.
The traditional tinted glass—a light shade of green—reflects only six percent of solar energy. Windshields that meet the proposed California standard have a multilayer nanotechnology film on the inside of the outer glass ply. One layer includes a glaze of metallic silver in combination with other metals. While it’s reflecting solar energy, it also blocks microwaves in the frequencies used by police, thereby making your radar detector useless.