Xenon high-intensity-discharge headlights employ xenon gas to produce a slightly bluish light, up to three times brighter than halogen headlights.
Technically a high-intensity-discharge (HID) light, xenon headlights are named for the inert gas they employ to amplify light produced by electricity jumping between two electrodes. HID lights don’t use a filament, as do incandescent headlights, and they tend to last two to three times longer. They also provide much more uniform intensity. Aim a set of xenon headlights at a wall, and you’ll see they define a sharp line at the top of the projected light pattern rather than the gradual fade common to conventional headlights. HID lights produce ultraviolet as well as visible light, which makes reflective highway signs glow more brilliantly.
Some drivers claim to be blinded by xenon lights’ intensity, a complaint we heard almost 20 years ago when halogen headlights came into being. Once drivers get accustomed to the bluish cast and no longer stare at them, they will probably become more accepting. Most vehicles that employ xenon headlights include a provision to ensure that they don’t blind oncoming traffic, even if the trunk is weighed down, which aims the headlights higher. Some use self-leveling technology in the lights themselves, and others have automatic leveling for the whole vehicle, which achieves the same goal.
The blinding blue lights you see on today’s roads may, in fact, be copycats. Shortly after the first xenon lights appeared on select BMWs in 1993, aftermarket companies began cranking out blue headlight bulbs and accessory lights. Most of these copycat bulbs are conventional incandescent bulbs with a blue coating or blue glass. Some include xenon gas for marketing purposes, but they still have a filament, not the gap-jumping arc. True HID lights operate on high voltages — 15,000 volts to jump the gap when first turned on and around 80 volts thereafter — so they require additional components, namely a type of transformer called ballast. HID offroad-style accessory lights that come with separate ballast are fairly common.
You’re sure to see more HID headlights in future years. Though they are currently rather expensive and often tied to premium option packages, the systems are smaller, lighter and allow for smaller headlamp assemblies — an advantage to vehicle designers and engineers alike. Though they operate on high voltage, the current they draw is actually around half that of conventional headlights, another plus. Then there’s the issue of performance; once you drive behind xenon headlights, you never want to go back.