In a first-ever study rating automotive headlights, the Insurance Institute for Highway Safety (IIHS) found that of 31 midsize vehicles tested, only one achieved a “good” rating. And that was on the top trim model of the Toyota Prius V.

Among the rest, about one-third (11) achieved an “acceptable” rating, while nine were rated “marginal” and 10 “poor.” The report called the results “dismal.” What’s shocking about this result is how broad-based the effect of dim vehicle visibility is in the automotive marketplace.

Consider the statistic that in more than 32,000 traffic fatalities in 2015, about 50 percent occurred at night or during dusk or dawn when visibility is lower. Clearly, the beams on most midsize cars are doing a poor job helping drivers see down a dark road at night.

The gap between the top-rated 2016 Toyota Prius V and all those at the bottom of the ratings is substantial, say officials from the IIHS. The Prius V, in top trim level, has LED headlights that were able to light up a straight roadway to allow the driver to sufficiently see a pedestrian, obstacle or bicyclist up to 387 feet ahead. The vehicle at that distance could be going as much as 70 mph and still have time to stop, per the study.

2016 BMW 3-Series

The “poor” rating afforded the 2016 BMW 3-Series, with its halogen headlights, was due to the fact that its headlights only illuminated 128 feet ahead. According to the study, at that distance, the car couldn’t be traveling at more than 35 mph and still have time to stop. The system’s high beams don’t reach 400 feet. The full IIHS headlight report says that a better combination for that same car is an LED curve-adaptive system with high-beam assist – although this still rates marginal.

The Issue Is More Complicated Than That

David Zuby, IIHS chief research officer, says that consumers can’t tell by just looking at the headlights of a car. “There’s a lot more to how well headlights help drivers see than merely the brightness of the bulb or even what type of bulb is used,” Zuby said.

“We found the same light bulb, depending upon what reflector of lens it’s paired with and how it’s mounted on the vehicle, can give you very different visibility down the road,” he said.

Common wisdom is that you buy a more expensive vehicle and get the best headlight technology, right? Not necessarily, says Zuby, who went on to say that headlights are more of a styling statement, not necessarily for their ability to illuminate the road great distances. Many of the vehicles with poor-rated headlights belong to luxury vehicles. The IIHS full report says “A vehicle’s price tag is no guarantee of decent headlights.”

The report points out that current government standards for headlights allow for huge variation in the amount of illumination that the lights provide in actual on-road driving.

IIHS testing headlights at night, Photo: IIHS

Specifics on the IIHS Test

The IIHS tested 82 different headlight systems in the 31 2016 midsize cars using set patterns on their test track at the Vehicle Research Center in Ruckersville, Virginia. A special device measured the light from both high and low beams as the cars were driven on five different approaches: straight, a sharp left curve, a sharp right curve, a gradual left curve and a gradual right curve.

The 2016 Toyota Prius V that earned the good rating was outfitted with the advanced technology package, which is only available in the top trim. In less-expensive Prius V trim levels, only standard halogen headlights without high-beam assist were available – those received poor ratings. Prius V drivers with halogen headlights, the report noted, would have to drive 20 mph slower in order to avoid a crash.

The value of high-beam assist is that it automatically adjusts the range of the headlamp for the distance of vehicles ahead or for oncoming traffic.

2016 Audi A3

Eleven vehicles earning acceptable ratings:

Nine vehicles that received marginal ratings:

2016 Cadillac ATS

Ten vehicles with poor headlight ratings:

Headlight Technology Advances

While the IIHS headlight study casts a rather dim light on what’s currently available to consumers, new advances in technology make this a good time to focus on the issue, says the Institute.

For example, high-intensity discharge (HID) or LED lamps have replaced halogen headlights. The greater availability of curve-adaptive headlights – which swivel in response to the driver’s steering input – is a promising trend. Research from the IIHS and the Highway Loss Data Institute (HLDI) shows that curve-adaptive headlights improve visibility and reduce crashes.

But in the IIHS headlight testing, three vehicles, the Cadillac ATS, Kia Optima and Mercedes-Benz C-Class, equipped with adaptive low and high beams earned poor ratings.

The IIHS’s headlight rating system doesn’t favor one lighting technology over another. It does, however, recommend systems that provide ample illumination without excessive glare for drivers of oncoming vehicles.

Consumers who want to determine which vehicles provide the safest visibility can check IIHS ratings at http://www.iihs.org.

Search used cars for sale and find the best deals near you at iSeeCars.com.