Your Car’s Headlights May Need Plenty of Improvement, Says IIHS’s First Headlight Rating

We have all heard about passive and active safety systems. But there are more fundamental factors in driving safety which includes car construction. Go deeper into this issue and you will find that headlight design in a modern car is not as simple as you may think.

The Insurance Institute for Highway Safety (IIHS) in the United States points this out after publishing their first ever evaluation and rating for 31 different vehicle headlights. A surprising find from their assessment is that a vehicle’s price tag is no guarantee of decent headlights. Many of the poor-rated headlights belong to luxury vehicles.

In fact, the best rating given out was ‘good’ which was for the Prius v. The best available headlights on 11 cars earn an acceptable rating, while nine only reach a marginal rating. Ten of the vehicles can’t be purchased with anything other than poor-rated headlights.

“If you’re having trouble seeing behind the wheel at night, it could very well be your headlights and not your eyes that are to blame,” says David Zuby, IIHS executive vice president and chief research officer.

The ability to see the road ahead, along with any pedestrians, bicyclists or obstacles, is an obvious essential for drivers. However, government standards for headlights, based on laboratory tests, allow huge variation in the amount of illumination that headlights provide in actual on-road driving. With about half of traffic deaths occurring either in the dark or in dawn or dusk conditions, improved headlights have the potential to bring about substantial reductions in fatalities.

Research has shown advantages for newer headlight types such as those that use HID and LED, but they don’t guarantee good performance. The Institute’s headlight rating system doesn’t favour one lighting technology over the other, but simply rewards systems that produce ample illumination without excessive glare for drivers of oncoming vehicles.

How the headlights are evaluated

The cars are tested as received from the dealer. Although some of the cars allow for directional adjustments, IIHS does not change the lamp’s aim since few vehicle owners will. Some manufacturers even discourage owners to do so.

Then the headlights are tested on track after dark at the IIHS Vehicle Research Centre. A special device measures the light from both low beams and high beams as the vehicle is driven on five different approaches: traveling straight, a sharp left curve, a sharp right curve, a gradual left curve and a gradual right curve.

Glare for oncoming vehicles also is measured from low beams in each scenario to make sure it isn’t excessive.

Engineers then compare visibility and glare measurements to those of a hypothetical ideal headlight system and use a scheme of demerits to determine the rating. Results for low beams are weighted more heavily than high beams because they are used more often. The readings on the straightaway are weighted more heavily than those on the curves because more crashes occur on straight sections of road.

A vehicle with excessive glare on any of the approaches can’t earn a rating above marginal.

The result

Since it is not abnormal for a particular model to have optional headlights, there are actually 82 headlight ratings for 2016 models even though there are only 31 vehicles. The Institute is rating every possible headlight combination as it becomes available from dealers.

The Prius v earns a good rating when equipped with LED lights and high-beam assist. To get those headlights, consumers must purchase the advanced technology package, which is only available on the highest trim level. When equipped with regular halogen lights and without high-beam assist, the Prius v earns a poor rating.

Among the 44 headlight systems earning a poor rating, the halogen lights on the BMW 3 series are the worst. A driver with those headlights would have to be going 56 km/h or slower to stop in time for an obstacle in the travel lane. A better choice for the same car is an LED curve-adaptive system with high-beam assist, a combination that rates marginal. (Luckily for buyers in Malaysia, BMWs from authorised dealers all come with LED lights).

Curve-adaptive systems don’t always lead to better ratings. The Cadillac ATS, Kia Optima and Mercedes-Benz C-Class all earn poor ratings even when equipped with adaptive low and high beams.

There was a surprise however; one of the best headlight systems evaluated has none of the new technology. The basic halogen lights on the Honda Accord 4-door earn an acceptable rating, while an LED system with high-beam assist available on the Accord earns only a marginal.