How many of you have driven the freeway and encountered these
bright blazing white lights that looked like they had a slightly
purple tint? I found out that these headlights weren't your
average typical halogen headlights but were something called HID.
It's a new headlight system that started out on higher end cars,
but as time goes by, the technology will get cheaper and its
availability will increase.
The first time I ever saw these lights was on a BMW 7 series, which was a few years ago. Now BMW is not the only car company with HID. Porsche, Mercedes, Lexus, Lincoln, Audi, and Acura have all now added HID headlights to their option lists, if not already standard equipment. HID is only available usually as an option on high-end cars. It will gradually find its way into mainstream autos.
Why the bluish light? Because it uses a gas filled bulb vs. filament. An electrical arc is passed through a capsule of gas, usually xenon. The purple light is a byproduct of using an electrical arc as light source. The spectral output is richer in blue and more like daylight than in halogen. The special blue light is not only prettier to look at but it increases the reflectivity of road signs and markers. These are essentially mini versions of stadium lights like at 3com park the difference is that these lamps would take minutes to light up if not for a sophisticated starter assembly which produces 75 % of full capacity within 2 sec. of switching on. They produce 70% more light than halogen. HID is 3 times more efficient than halogen. They use far less energy than standard halogen bulbs (35w vs. 55w). HID bulbs last 3 to 5 times longer than standard halogen bulbs.
These are available in some places as retrofit but are very expensive usually around 800 dollars. The disadvantage to this HID light is that it causes glare to oncoming drivers who stare too long. These lights are specifically focused on the right side of the road as to prevent this but the lights still attract more attention that normal lights, which in turn creates the glare.
Halogen lights by the way, are used in most cars on the road today. This system is the standard right now.
Right now impostors are numerous and are usually halogen bulbs coated with a bluish tint sometimes called ion/diamond blue or dichroic bulbs. The easiest way to tell is to see what kind of car it is, if it's a Honda civic, chances are, it's just a ion blue bulb. Since HID is only available on higher end cars. I've seen strange combinations of colors in bulbs like purplish yellow, reddish blue, blue green/white. These are all the rage since they promise to look like HID for a cost of $35 as opposed to $800. These bulbs are not only illegal, but they also give off less light since the tint filters out all usable light except for the colors in the tint.
Next time you see a car with funny colored headlights, you can feel special because now you know whether it's a colored halogen bulb or the genuine HID bulb. So now I hope I shed some light on this eye-catching feature on cars.