An Update on Headlights

By Roger Sitterly

Over the course of the past few years, the Insurance Institute for Highway Safety has developed a ratings system for headlight effectiveness. To date, the tests have not included a MINI of any model. Although tests have been performed on the 2016 model year BMW 2-series and BMW 3-series, I don’t know if the headlights used on those BMW products are identical to what comes on different models of MINI.

Two conclusions can be drawn from the IIHS tests so far (these apply only to 2016 model year vehicles):

First, the reason you can’t see well at night is quite likely related to the quality of the headlights that are on your car rather than to the ability of your eyes to see well. The IIHS report quoted David Zuby, IIHS executive vice president and chief research officer saying “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.” Although headlight technology has improved significantly since the decline (and, one hopes permanent death) of sealed beam headlights, having high tech headlights (halogen, high-intensity discharge, or LED headlights) is no guarantee of getting good illumination of the road after dark.

Second, the ability of those headlights to properly illuminate the road in front of you appears to have absolutely zero correlation to the price of the vehicle. Specifically, none of 31 vehicles tested in their 2016 model configurations earned anything better than a “good” rating, and only the Toyota Prius with LED headlights and high-beam assist managed to score that well. At the other end of the ratings, the Cadillac CTS, Mercedes Benz C-class, Mercedes Benz CLA, Buick Verano, and VW Passat were among the 10 cars tested that earned a “poor” rating. The Honda Accord 4-door, Audi A3, Lexus ES, and Mazda 6 were among the 11 cars tested that earned “acceptable” ratings, while the Audi A4, Lincoln MKZ, BMW 2-series and BMW 3-series were among the nine cars tested that earned a “marginal” rating. The BMW 3-series with halogen headlights was the worst-performing vehicle tested.

How the IIHS conducted its tests

Headlights were evaluated on the track after dark at the IIHS Vehicle Research Center. A special device measured the light from both low beams and high beams as the vehicle was driven on five different approaches: traveling straight, a sharp left curve, a sharp right curve, a gradual left curve and a gradual right curve. Headlight glare produced for oncoming vehicles was also measured from low beams in each scenario to make sure it wasn’t excessive.

Headlights were tested as received from the dealer. Although the vertical aim of headlights can be adjusted on most vehicles, IIHS didn’t change headlight aim because experience has shown that few vehicle owners ever do, and also because some manufacturers advise consumers not to adjust the aim of their car’s headlights.

After a vehicle was tested on the track, IIHS engineers compared its visibility and glare measurements to those of a hypothetical ideal headlight system and used a scheme of demerits to determine the rating. Results for low beams were weighted more heavily than results for high beams because low beams are used more often in real-world driving. The readings on the straightaway were weighted more heavily than those on the curves because IIHS has found that more crashes occur on straight sections of road than on curves.

Vehicles equipped with high-beam assist, which automatically switches between high beams and low beams depending on the presence of other vehicles, could earn back some points taken off for less-than-ideal low beam visibility. This credit was given only for approaches on which the glare threshold wasn’t exceeded and on which the high beams provided additional visibility compared with the low beams.

A vehicle with excessive glare on any of the approaches could not earn a rating above marginal no matter how well that car’s lights illuminated the road ahead.

The IIHS defined the threshold of “adequate illumination” as 5 Lux. “Lux” is the standard International System of Units measure of luminous emittance and equates to one lumen per square meter of surface. To put this in perspective, a normal incandescent 60-watt light bulb emits approximately 800 lumens of light (when measured very close to the bulb).

The following illustration is the IIHS depiction of the Prius LED headlights that earned a “good” rating.


Compare that image with the comparable image for the BMW 3-series with halogen headlights (below).


Making life difficult for consumers

What makes life even more difficult for consumers is that the headlights on different vehicles of the same make, model, and model year may differ significantly in their usefulness. Specifically, the 2016 BMW 320, 328, 330, and 340 models equipped with LED reflector headlights and with the “Lighting” package were all rated as “marginal” while the very same vehicles equipped with LED reflector headlights and with the “Premium” package were all rated as “poor”.

Another problem facing consumers is that having the latest high-tech (LED) headlights is no guarantee that you’ll be able to see better at night. For instance, the Honda Accord four-door sedan with halogen headlights earned an “acceptable” rating, while the same car with LED headlights and high-beam assist earned only a “marginal” rating.

Absent comparable test data for the headlights on various models of MINIs, it is impossible to say exactly how well or poorly the different headlights available from MINI perform in the real world, though it’s likely some are better than others (for instance, for reasons related to design and perhaps installation constraints, the headlights on a Countryman might earn a higher or lower IHHS rating than those on a Hardtop). However, I think it is important for all of us, as current owners, to consider seriously the question of whether or not the headlights on our cars enable us to see as well as possible when driving at night. Personally, the HID headlights on my 2004 “S” (low beam only – the 2004 cars with HID headlights have halogen high beams) provide what I believe to be an acceptable amount of forward vision on low beam, though I’d love to have IHHS-comparable data for them. However the lights provide an unacceptable amount of forward vision on high beams which is why I’ve added the four driving lights on the front of my car.