WASHINGTON -- Mercedes, Lexus and other high-end cars have an eye-catching feature that may soon be found on everyday automobiles: bright, bluish headlights.
High-intensity discharge lamps, which started as a $1,000 option, provide about twice the brightness of ordinary headlights, closely approximating daylight. At the same time, HID lights use less power and can last for 100,000 miles of driving time.
Some experts believe the lights will soon displace halogen headlights, the current technology, just as other lighting systems bettered the oil lamps first used on cars.
"HID is kind of a prestige thing, but over time, and it will be a relatively short period of time, people are going to expect them on their car," said George Peterson, president of AutoPacific, an automotive consulting company.
Some motorists have complained about being dazzled by the HID lights. A lighting specialist at the National Highway Traffic Safety Administration said some people are more sensitive to light that has a blue cast. But he said the lights meet the same intensity and beam shape standards in place since 1978, the last time the government made a major revision of its standards.
Halogen lamps on most of today's cars generate light by heating a tungsten filament inside a halogen capsule. The halogen gas helps prevent blackening of the capsule as the filament slowly burns out.
High-intensity discharge lamps operate more like vapor-filled streetlights. They don't have a filament, but create light by zapping an arc between two electrodes. That arc excites a different kind of gas, usually xenon, which in turn ignites metallic salts.
The lights appear brighter to the eye because of their spectral content. Although their beams travel no farther or wider than those produced by halogen lights, they contain more light at the margins. It fades less at the edges. It also appears blue.
More powerful headlights have long been popular in Europe, where driving speeds can double those in the United States. Over the past few years, American car buyers have started ordering HID lamps as an option.
Eager to tap the marker, lighting companies are now investigating two other options for HID lamps. One is as a replacement bulb for existing halogen headlights. The other is as an auxiliary light, such as a fog lamp.
"The light is amazing and customers love them," said Lou Brown, a salesman at a Lexus dealership in Alexandria, Va. "You really have to drive the car at night to appreciate the difference."