Headlights are one of the most overlooked safety features on a vehicle, yet research from the Insurance Institute for Highway Safety shows that their performance can have a measurable effect on real-world crash rates.
Vehicles equipped with good-rated headlights experienced 19% fewer nighttime single-vehicle crashes than vehicles with poor-rated headlights.
The difference was even more notable for pedestrian crashes, with Good-rated headlights associated with 23% fewer nighttime pedestrian crashes. IIHS reached these conclusions after analyzing police-reported crashes while controlling for mileage, driver-related risk factors, road conditions, and other variables.
The findings matter because nighttime driving remains substantially more dangerous than daytime driving. About half of traffic deaths occur in darkness or around dawn and dusk. Better headlights cannot eliminate nighttime risks, but they can give drivers more time to recognize hazards and react.
The research also challenges the idea that excessive brightness is the biggest headlight problem. IIHS says inadequate road illumination is a much more significant crash-related issue than glare from other vehicles.
Why Better Headlights Reduce Nighttime Crashes
IIHS began its headlight rating program after finding that many systems meeting federal requirements still provided inadequate illumination. The organization evaluates headlights based on how effectively they illuminate the roadway rather than simply measuring how much light they produce.
The ratings are technology-neutral. LED, HID, and halogen headlights are judged according to their actual performance. A vehicle does not automatically receive a good rating because it uses LEDs or adaptive lighting.
IIHS measures how far low and high beams illuminate the road on straight sections and curves. It also accounts for excessive glare because a headlight that illuminates the road effectively but blinds approaching drivers can create another safety problem.
The real-world crash study found that good-rated headlights were associated with a 19% lower nighttime single-vehicle crash rate than poor-rated systems. Acceptable-rated headlights were associated with approximately 15% fewer crashes, while marginal-rated headlights showed about a 10% reduction compared with poor-rated systems.
IIHS also found that good-rated headlights were associated with a 29% reduction in nighttime crashes involving driver injury. Tow-away crashes and pedestrian crashes also declined by roughly one-quarter.
The pedestrian finding is particularly important. A driver traveling on an unlit road can encounter someone difficult to see against a dark background. Better headlights can illuminate more of the roadway and provide additional time to identify and avoid the hazard.
That does not mean headlights alone prevent 23% of pedestrian crashes. The figure describes the difference in observed crash rates between vehicles with good- and poor-rated systems after accounting for other relevant factors.
Driver behavior remains critical. Speed, distraction, impairment, and failure to yield can overwhelm even an excellent headlight system. But the evidence demonstrates that the equipment itself matters.
Headlight performance is especially important around curves. A system may illuminate a straight road reasonably well while leaving the driver’s path around a bend poorly lit. That is why IIHS evaluates where headlights actually illuminate rather than simply measuring brightness directly ahead.
Headlights Have Improved Dramatically Since 2016
The crash reduction becomes even more significant when viewed alongside the industry’s progress in headlight performance.
When IIHS launched its rating program, only about 1% of tested 2016 systems were rated Good. Another 18% were acceptable, 19% marginal, and 62% poor.
By 2025, 51% were Good, 33% Acceptable, 6% Marginal, and 10% Poor. In other words, 84% of tested systems were Good or Acceptable, compared with only 19% in the first year.
Current 2026 data show 46% of tested systems earning good ratings, while approximately 17% are marginal or poor. That represents a slight year-to-year change from 2025, but the long-term improvement remains enormous.
IIHS credits its ratings program with encouraging manufacturers to improve headlight designs. The organization also strengthened its Top Safety Pick requirements so automakers could not qualify for the highest safety recognition while offering consumers poor-performing headlights.
Manufacturers have increasingly moved toward better-performing standard systems rather than offering major differences between trims. That matters because an excellent headlight is less useful from a safety standpoint if it is available only on an expensive version of a vehicle.
LED technology has also become widespread, offering advantages in efficiency, packaging, and durability. But IIHS emphasizes that its ratings remain technology-neutral. A poorly designed LED system can still receive a poor rating, while another technology can perform considerably better.
For shoppers, this means terms such as “full LED,” “projector,” “adaptive,” and “automatic high beam” should not be treated as guarantees of performance. They describe equipment rather than how effectively the complete system illuminates the road.
Visibility Matters More Than Glare
Modern headlights are frequently criticized for being too bright, particularly by drivers facing newer SUVs and trucks with higher-mounted lamps. IIHS does not dismiss those concerns, but its research indicates that glare is a much smaller crash problem than inadequate visibility.
A 2025 IIHS analysis of police-reported crashes from 2015 through 2023 found headlight glare was identified as a contributing factor in only one or two out of every 1,000 nighttime crashes.
For comparison, the crash reduction associated with good-rated visibility is substantial. IIHS therefore argues that improving illumination should remain the primary priority while controlling glare remains an important secondary goal.
Manufacturers have made progress on both fronts. For 2026 model-year headlights, only 5% of systems tested had excessive glare, compared with 21% in 2017.
That suggests modern headlight development is not simply about producing more intense beams. Engineers are increasingly focused on directing light where it is useful while limiting the amount reaching other drivers’ eyes.
The remaining marginal and poor systems show that the market has not reached a point where every new vehicle provides excellent nighttime illumination.
For buyers, that difference can be difficult to identify during a dealership visit. Most test drives occur during daylight, and even an evening drive may not reveal how well headlights perform around curves or on unlit roads.
Independent testing therefore provides information that a conventional test drive cannot. The difference between good and poor systems is not merely theoretical.
IIHS found that good-rated headlights were associated with 19% fewer nighttime single-vehicle crashes and 23% fewer nighttime pedestrian crashes than poor-rated systems. These are population-level differences, not guarantees that an individual vehicle or driver will avoid a crash.
The industry’s progress since 2016 is encouraging. Good-rated headlights have gone from being extremely rare to representing roughly half of tested new-vehicle systems, while marginal and poor systems have fallen dramatically.
The next challenge is closing the remaining gap. As adaptive lighting and automatic high beams become more common, manufacturers have more tools to improve nighttime visibility.
The goal should not simply be brighter headlights but better-controlled illumination that helps drivers see pedestrians, animals, curves, and obstacles without creating unnecessary glare.
For consumers, the key takeaway is simple. Headlight performance should receive just as much consideration as crash-test ratings and automatic emergency braking when assessing a vehicle’s safety.
A vehicle that performs well during the day but provides poor visibility at night leaves its driver with less information when the road is hardest to see.
The IIHS research shows that the difference can have measurable consequences. Good headlights are associated with fewer nighttime crashes, and the 19% reduction in single-vehicle crashes and 23% reduction in pedestrian crashes provide compelling evidence that better lighting is not simply a convenience. It is an important part of vehicle safety.
What Drivers Should Look For
For drivers, the most useful lesson is that headlight performance should be evaluated as a complete system rather than by a single feature. Beam reach, performance around curves, high-beam effectiveness, and glare control all contribute to how useful a headlight is at night.
This is particularly important for people who frequently drive on rural roads, poorly lit highways, or routes with frequent curves. These environments give drivers less help from street lighting and make forward visibility more important.
Automatic high beams can also be useful because they make it easier for drivers to use additional illumination when conditions allow. However, IIHS testing shows that advanced features cannot compensate for weaknesses in the underlying headlight system. The hardware still needs to illuminate the roadway effectively.
Drivers should also remember that headlights can become less effective over time. Lens condition, aiming, and other maintenance issues can affect how much useful light reaches the road. A vehicle that originally performed well can therefore provide weaker nighttime visibility if its lighting system is damaged, poorly aimed, or deteriorated.
Good headlights give drivers more information sooner, which can create valuable additional time to recognize hazards and respond.
