Within the next three years, experts will grade car headlights not by how much they resemble a Swarovski crystal—or as in the case of the Mercedes S-class coupe (pictured above) how many they actually have—but by how they function. While the federal government specifies brightness, alignment, and other basic technicalities (like making it illegal to drive with strobes), at no point have headlights ever been evaluated for their effectiveness.
The National Highway Traffic Safety Administration will test headlights when it overhauls its New Car Assessment Program for 2019, and the Institute for Highway Safety will incorporate similar results into its Top Safety Pick categories starting next year. Until that happens, is it worth springing for advanced xenons and LEDs on your next car?
The IIHS doesn’t think so. In its testing of a random mix of 31 mostly midsize cars across premium and non-premium segments, only the Toyota Prius V and its LED projector lamps scored the maximum “good” rating. The standard halogen lights on the BMW 3-series rated “poor” (optional LEDs scored just “marginal”) while the Kia Optima’s received a “poor” rating and also delivered the most glare to oncoming drivers. (See the full results here.) The IIHS ran five test—one straight, a set of 500-foot radius left and right curves, and another set of 800-foot radius curves—and compared them what it considers a “hypothetical ideal.” On all tests, the IIHS considers an optimal distance required for a driver traveling at 65 mph to spot an obstacle in his lane and brake to a complete stop.
In this straightaway test, the “ideal” low beams can illuminate roughly 325 feet for the right-hand beam and just under 200 feet for the left-hand beam (since we drive on the right, the left-hand beam must dip further to avoid dazzling oncoming drivers). On curves, the driver is presumed to be traveling at 40 mph and here, assuming the use of adaptive cornering headlights, the low beams would be able to reach roughly 190 feet and 225 feet in either direction. Headlights must also reach five lux (the measure of lumens per square meter, in this case the equivalent of five times the ground surface illumination of moonlight). Light sensors placed 10 inches from the ground (and three feet, seven inches for oncoming glare) provide the measuring sticks, and proper testing presumes a new moon and no ambient light. Unlike the testers at Consumer Reports, the IIHS does not adjust vertical aim before conducting tests, in a preference to keep the cars (purchased at dealers) as stock as possible.
At the moment, there is no one measure by which headlights are deemed “safe,” and while the IIHS methodology is certainly promising, we can only hope it contributes to a final standard that all automakers and NHTSA can agree is sound. But without speaking to numerical tests, we’ve found most optional headlights to offer the brighter, whiter visibility that makes driving at night, especially at higher speeds, more comfortable and worthy of their price. If your car dealer stays open late and headlights are that important, be sure to test drive your potential new ride after sundown.
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