Car headlights in addition to tungsten light, halogen lights, xenon lights what ah?
There are sodium lamps into a small amount of sodium lights when the heat (may react with a substance) yellow, because the yellow light of the best transmission, easy to see, easy to filter
There are LED (light-emitting diodes) such as the new Audi A8
At present, more practical to say that you kind of, and some more conceptualization, can not put into mass production
