No matter how many carrots you eat, you will never see in the dark as well as high-tech infrared systems from Mercedes and BMW.

By Jim Henry

Technology is making it easier to see in the dark, notably with so-called “night vision” systems from BMW and Mercedes-Benz. Lexus also has a system, but is dropping it starting with the 2008 model year.

All these pricey systems rely on infrared light, which is invisible to the naked eye. The systems allow you to see better and farther at night — especially to see pedestrians or animals in or near the road. The infrared light also won’t blind oncoming traffic the way white light does.

During a recent test drive, the BMW system disclosed a bicyclist dressed in dark clothing, who was riding on a dark, tree-lined sidewalk with no streetlights and no headlight or reflectors on his bike. He would have been easy to overlook without the high-tech help. Instead, he showed up as a brightly glowing image zipping in and out of the trees, on the television-like NightVision dashboard display screen in a BMW 650i Coupe. However, though the technology seems to work pretty well, the display in the BMW takes some getting used to. To a lesser extent, so do the Mercedes and Lexus systems. The BMW system, which is optional on the 6 Series and on some 7 Series and 5 Series models, has a suggested retail price of $2,200. The Mercedes system is standard on V-12 versions of its flagship S-Class sedan and CL-Class coupe. For somewhat less-expensive S-Class models, the Mercedes Night View Assist system is part of an expensive options package for the 2008 model year. For the 2007 model year, it was a standalone option on some S-Class models for $1,775 suggested retail.

The Lexus system is a $2,200 option on the 2007 LX 470. However, the order rate is so low that the company is dropping this option when the LX 470 is replaced by the LX 570 early in calendar-year 2008.

Passive and Active Night Vision Systems

There are two basic approaches to automotive night vision systems: passive and active.

A passive system like BMW’s detects heat. Technically speaking, its camera detects and displays contrasts in heat, such as a warm body against cold night air, explains Stuart Klapper, business director of Autoliv Night Vision. (Sweden-based supplier Autoliv makes the BMW system.)

The passive system does not send out a beam of light. It passively collects infrared and displays as a “glow” anything warmer than the background, like pedestrians and animals.

The other major type of night vision is an active system, like the one Mercedes-Benz and Lexus offer. (Germany’s Siemens VDO Automotive makes the Mercedes system. Lexus typically doesn’t disclose its suppliers, according to a spokesperson.) A beam of infrared light illuminates the road ahead, while a camera that can “see” infrared picks up the reflected infrared light and shows the results on a display in the instrument panel.

An active system does not detect heat, but it does “see” anything illuminated by the infrared light, whether hot or cold.

Pros and Cons of Night Vision on Vehicles

There are pros and cons to both the active and passive approaches.

The active display looks like the “real world,” only sharper, more clear and in black-and-white. In fact, the display looks so normal that it’s not always obvious that it can see better than the naked eye, even though it can. According to Mercedes, a crash-test dummy visible with low-beam, bi-xenon headlamps at 160 meters becomes visible with Night View Assist at 210 meters.

The competing passive display has a greater claimed range — up to 500 meters in ideal conditions — but the display is surreal-looking, like watching a black-and-white negative. Hot objects show up bright, including the things that are most critical to see, like cyclists, people at a bus stop, dogs and deer.

However, a passive system also displays an unearthly glow underneath the car in front of you, which is caused by the hot exhaust system. And power-line transformers mounted on poles show up as mysterious white cylinders among the trees.

Cold objects — that is, objects that are the same temperature as the background — may not show up at all. A bright, highly reflective stop sign a few feet away may show up on the display as a nearly invisible black octagon against a black background.

Weighing the Tradeoffs

Is a night vision system right for you? That depends. The tradeoff is between the high price of night vision versus how often you’re likely to use it, as well as how easy it is to use. If you drive often on unlighted streets where there are likely to be pedestrians or animals in the road, it might be a worthwhile option, especially if you feel comfortable with the technology.

Meanwhile, conventional white headlights are improving, with the spread of brighter bi-xenon lights and “adaptive” headlights that bend the beam of light around corners when turning.

And Autoliv’s Klapper says that a so-called “fused” system that combines both active and passive features could be the next step in night vision technology.

So stay tuned!

Bio: Jim Henry is a veteran freelance automotive writer. He was a one-man bureau in New York City for Detroit-based Automotive News for many years. He is also a past president and a board member of the International Motor Press Association.

The views and opinions expressed in this article are solely those of the author and not necessarily those of Progressive Casualty Insurance Company or its affiliates.