Flashing mirrors are only part of a larger technology push that is changing the look and function of a car’s lights. Carmakers call these lights and lenses jewelry, and cars are increasingly adorned with more of them as new plastics, electronics and manufacturing methods change necessary but dull structures into bright and sexy selling points.
Most noticeable may be high-intensity discharge, or H.I.D., headlights, whose blue-white glow contrasts sharply with the yellow light of ordinary tungsten filament headlights. The xenon-gas-based H.I.D. lights generate a spectrum that is much closer to sunlight, so they appear brighter, giving drivers who use them a visual advantage after dark.
”The H.I.D. is more expensive, but you get two and a half times the light,” said Mark Evans, engineering group manager of exterior lighting for General Motors.
The H.I.D. headlight requires a different design. In one form, it resembles a bulbous round lens deep inside a shiny headlight module. This is called a projector headlight, and it works much like a slide projector. Instead of one light for ordinary driving and a separate high-beam headlight for longer-distance vision, the projector lens uses a single bulb and moves the reflector shield surrounding it to change the light focus.
H.I.D. lights have been common on European luxury cars, and Cadillac cars will soon carry them as standard equipment. Ford’s Lincoln line is also using them.
A BLENDING of North American and European approaches is emerging, too, in the way light is beamed in front of a car. American designers have traditionally used a diffuse focus, with the pool of light created by the headlights fading at the far reaches, while European designers favor a precise cutoff at a set distance for the headlight beam to reduce surplus glare. As headlamps become brighter and more engineered, automakers are tending to the European approach.
Even where the specialty lights are not yet in use, headlight assemblies themselves have been changed significantly. Where once a headlight bulb existed, today there is a multifaceted lens assembly carrying four or more separate bulbs. These can include a low beam, a high beam, a daytime running light and a special turning lamp that throws white light in the direction the car is about to go.
Another star player of the emerging design revolution is the light-emitting diode, or L.E.D., the same green, amber or red solid-state widget that has been used for decades in computer equipment and home appliances. In the 1990′s, technology advances created reliable high-intensity diodes, and carmakers were charmed.
”The L.E.D.’s illuminate about 200 milliseconds faster than a light bulb, which doesn’t sound like much but equals about a full car length at 65 miles per hour,” said Al Gagne, an engineering spokesman at G.M.
Mr. Gagne said the L.E.D.’s created faster taillights to help prevent collisions, and soon might be bright enough to use in headlight assemblies.
In addition to being fast to light up, L.E.D.’s have other advantages. They use only 20 percent of the electricity it takes to power fragile and failure-prone light bulbs. They generally last longer than most cars. They emit less heat than bulbs, which frees car designers to replace huge, clunky taillight assemblies with slim, elegant ones.
The first L.E.D. taillights were crude industrial chic, mostly for delivery trucks and tractor-trailers. Automakers began using them in the extra taillight called a chimsel, for center high-mounted stop lamp, but as reliability increased, the diodes moved on. G.M. put its first L.E.D. taillights on the 2000 Cadillac DeVille.
”You’re going to see G.M. come out with designs that showcase the L.E.D.’s a little bit more,” Mr. Gagne said.
With the appropriate glues and heat-dissipating design, future taillights might become a stick-on external component, freeing trunk space and simplifying the use of sheet metal, which now must be pierced to hold lamp assemblies.
The diodes have also been popped into side mirrors to function as extra turn indicators. Mercedes-Benz uses L.E.D. technology for both brake lights and extra turn signals — called repeaters — on its S-Class sedan and CL-Class coupes.
Signal repeaters on the front sides of European cars have been required for a long time, but Mercedes-Benz came up with a twist, putting signal repeaters in the front of the mirrors on the 2000 S-Class.
Muth Mirror Systems of Sheboygan, Wis., an auto supplier, has a side mirror that flashes a chevron-shaped line of diodes when a turn signal is activated; they have appeared as original equipment on premium Ford trucks and sport utility vehicles, including the Excursion. The mirrors are sold as ”power safety signal mirrors” on the 2002 Windstar minivan, in which they also flash in the side mirror to show that a sliding door is open and passengers may be exiting.
The Donnelly Corporation of Holland, Mich., has its bulb-based side mirror signals installed on G.M.’s GMC 360 sport utility vehicles, which sell as the TrailBlazer, Envoy and Bravada. Donnelly’s mirrors combine turn signals and ”puddle lights,” an increasingly popular feature that shines a small spotlight on the ground near car doors to help the driver and passengers avoid stepping into a mess after dark. The light is activated by opening the driver’s door or by a remote entry key fob.
THE Insurance Institute for Highway Safety says there is no research yet to indicate that the side-mirror signals improve safety. Not enough cars equipped with the systems are on the road to measure their effectiveness, said Russ Rader, a spokesman for the institute.
But if the signals are even somewhat as effective as daytime running lights or chimsel brakelights, side-mirror signaling and advanced headlight and brakelight systems may end up saving hundreds of lives and millions of dollars in property damage annually.
Though many drivers do not like them, automotive researchers say that daytime running lights have reduced multiple vehicle crashes during daylight hours. A study completed last year by the Insurance Institute for Highway Safety found a 3 percent decline in such crashes in a nine-state area during the time period that daytime running light systems were introduced.
The figures seem to show that lighting cars for visibility is beneficial. The systems have typically used either regular headlamps at half their normal brightness or special marker lamps near the headlights. Carmakers are now experimenting with cutting down the brightness to try to make daytime running lights more appealing to customers.
The same safety logic has led to the introduction of what are called rear fog lights. The lights are actually an amplified version of the typical taillight, and they are meant to brighten the rear marker lamps of a car so that drivers coming up from behind will notice a car sooner in foggy or hazy conditions.
Lighting has become so important, automotive executives say, that lighting engineers are now routinely included during the earliest phases of car design and production. Concept cars that once were displayed with generalized, nonroadworthy head and taillamps are now displayed in all their shining glory.
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