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Nearly half of vehicle deaths occur in low-light conditions. However, real-world headlight testing is not included in vehicle safety scores. The Insurance Institute for Highway Safety (IIHS) began evaluating headlights this year, rating midsized cars in March and small SUVs in July. The results proved that most headlights need improvement.

The new evaluation system being utilized by IIHS is foreshadowing a new vehicle assessment system that will be fully put in place in 2019. For 2017, a vehicle will need to receive a rating of Acceptable to qualify for the IIHS Top Safety Pick award. The National Highway Traffic Safety Administration has taken notice of the IIHS study and is proposing the addition of lighting in its five-star safety ratings.

David Zuby, executive vice president and chief researcher at IIHS, told the Associated Press that government headlight regulations have remained “essentially unchanged” since the 1960s. He said, “In the standard, they are measuring the light coming out of the light source – right in front of the light bulb, in essence – and not looking at how the light is projected down the road, which is what our tests do.” 

[Read: There Is a Big Difference Between Car Headlights]

IIHS testing measures the distance that a headlamp's light travels in real-world situations, covering multiple approaches. The light is assessed by a set of sensors 10 inches off the ground, and another set 3 feet 7 inches off the ground, to measure oncoming glare. Both low beams and high beams are evaluated, but IIHS only assesses oncoming glare with the low beams. Headlights are tested as delivered by the dealer, although most should be adjusted, it is assumed that many drivers do not perform this task.

Headlights are expected to reach five lux, the unit of measurement for how bright a light is, at “ideal” distances. For comparison, a full moon on a clear night illuminates the roadways about one lux. The five tests include a straightaway, two graduals curves, and two sharp curves. Straightaways are assessed at 65 mph and curves at 40 mph. The curves are assessed in both left and right directions.

Midsize Cars

Toyota Motor Sales, U.S.A., Inc.

Of the 31 cars evaluated in the 2016 midsize car testing, only one vehicle, the Toyota Prius v, earned a Good rating. IIHS assessed 82 total headlight combinations, and 44 received Poor ratings. Even the Toyota Prius v was considered Poor without the advanced technology package, which is only available on the top trim. Without the package, the Prius comes equipped with standard halogen bulbs, but no high beam assist.

While many advancements in lighting technology are becoming available, such as LED lamps, high-intensity discharge (HID) lamps, and curve-adaptive headlights, good performance is not guaranteed by these innovations. IIHS does not base ratings on the type of lamps or technology; they simply measure the results.

The only new technology that IIHS has noted is helpful is high beam assist, which switches from low beams to high beams when other nearby vehicles are not present. It can increase a vehicle’s ratings due to further visibility and works to decrease overuse of high beams in unsafe situations.

One of the best systems tested was on the Honda Accord sedan, which has none of the new technology, with only halogens present. The Cadillac ATS, Kia Optima, and Mercedes-Benz C-Class, all with curve-adaptive technology, earned Poor ratings. The BMW 3-Series received the worst ratings of all cars tested.

Small SUVs

Mazda North American Operations

Small SUVs fared even worse than the midsize cars in IIHS evaluations. Not a single vehicle, regardless of trim, earned a Good rating. Of the 21 vehicles tested, 47 headlight combinations are available and over half received Poor ratings.

The Mazda CX-3 had the best headlights, according to IIHS. However, like the Prius, the CX-3 headlight system receiving the top ratings is only available on the top-tier Grand Touring trim. The top-trim Mazda is equipped with optional LED lights that are curve-adaptive and offer high beam assist.

Three other vehicles received Acceptable ratings: the Ford Escape, Honda CR-V, and Hyundai Tucson, and none of them have curve-adaptive technology. High beam assist is only present on the Escape. The Honda HR-V received the worst ratings, and the HR-V has no available options for upgrading out of the Poor category.

Many SUV headlight systems were considered to have a problem with glare. IIHS Senior Research Engineer Matthew Brumbelow explained, "Glare issues are usually a result of poorly aimed headlights. SUV headlights are mounted higher than car headlights, so they generally should be aimed lower. Instead, many of them are aimed higher than the car headlights we've tested so far."


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It is very important that those purchasing a vehicle consider headlight ratings and select the best headlight available on the car they're buying. Hopefully, over time, the top-rated headlight combinations will become available as options on base models across the industry. The best-case scenario will include Acceptable headlights as standard on base models. Brumbelow said, "We're optimistic that improvements will come quickly now that we've given automakers something to strive for."

Consumers can search models on For vehicles tested, the Institute provides detailed headlight information. Included for each model is a convenient graph showing the rating results. Also, for each vehicle, the website clearly states “only certain trims,” and upon opening the headlight rating tab, trims and headlight systems are specified. IIHS plans to rate pickup truck headlights next.