The Toyota Prius v is the only midsize car out of 31 evaluated to earn a good rating in the Insurance Institute for Highway Safety’s first-ever headlight ratings.
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.
A vehicle’s price tag is no guarantee of decent headlights. IIHS found that many of the poor-rated headlights belong to luxury vehicles.
“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.
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, according to the IIHS.
IIHS said recent advances in headlight technology make it a good time to focus on the issue as high-intensity discharge (HID) or LED lamps have replaced halogen ones in many vehicles and curve-adaptive headlights, which swivel according to steering input, are also becoming more common.
IIHS research has shown the new headlight types have advantages, but they don’t guarantee good performance. The Institute’s headlight rating system doesn’t favor one lighting technology over the other, but simply rewards systems that produce ample illumination without excessive glare for drivers of oncoming vehicles.
One Good Rating Out of 82
Vehicles can be equipped with different headlights, so there are a total of 82 headlight ratings for 2016 models even though there are only 31 vehicles. The Institute said it 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.
“The Prius v’s LED low beams should give a driver traveling straight at 70 mph enough time to identify an obstacle on the right side of the road, where the light is best, and brake to a stop,” says Matthew Brumbelow, an IIHS senior research engineer. “In contrast, someone with the halogen lights would need to drive 20 mph slower in order to avoid a crash.”
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 35 mph 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.
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.
In the case of the Optima, a big problem is glare. Its curve-adaptive system provides better visibility than its non-adaptive lights, but produces excessive glare for oncoming vehicles on all five low beam approaches.
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.
IIHS tests headlights after dark on a track at the IIHS Vehicle Research Center. Researchers use a special device that 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. It also measures glare for oncoming vehicles from low beams in each scenario to make sure it isn’t excessive.
IIHS Headlights Rating 2016 Midsize cars
Best available headlight system for each model
|Toyota Prius v|
|Honda Accord 4-door|
(built after Nov. 2015)