Do the New Auto-Safety Devices Prevent Car Crashes?

Date: November 1, 2012      Publication: Bottom Line Personal      Source: . .      Print:

Some do…Some don’t

The latest automotive-safety technologies don’t just help us survive car crashes—they actually can prevent crashes. The devices include systems that automatically nudge a vehicle back into its lane when it drifts…or hit the brakes for us when a collision is imminent.

But are they truly worth their cost? Some of the latest, greatest devices tend to be offered only on high-end models or in option packages that can add thousands of dollars to the price of a vehicle.

Example:In a 2013 Ford Flex wagon, if you want adaptive cruise control, a safety feature that maintains the distance between your vehicle and the car ahead, you must choose the Limited model—which costs $8,345 more than the SE model—and add a $2,500 option package.

Here’s how to decide which of the latest safety technologies are truly worth the cost…

Adaptive cruise control doesn’t just lock in your speed. When engaged, it uses radar or lasers to track the vehicle ahead of you in traffic, then maintains a safe following distance. If the car ahead slows, your car will slow, too, as you approach an unsafe distance.

Examples:Most of the major automakers are in the process of developing and rolling out adaptive cruise control for more mainstream vehicles. In many cases, it still is limited to the high-end cars in their fleets, but that is rapidly changing. Mainstream 2013 vehicles offering the technology include some more expensive versions of the 2013 Subaru Legacy and Outback and 2013 Ford Edge, Explorer, Flex, Fusion and Taurus.

Verdict: Adaptive cruise control can be very useful if you do a lot of highway driving—but not if that highway driving is done in heavy traffic. These systems require a fairly long following distance. In heavy traffic, other drivers will continually pull into the space that is left in front of you—and each time they do, your adaptive cruise control will slow your vehicle, which can make for annoying and fuel-inefficient travel.

Adaptive headlights turn slightly when the steering wheel is turned or when a turn signal is engaged, helping drivers better see the road ahead at night. It’s not a new idea, but it is only now coming into widespread use. Adaptive headlights often are combined with high-intensity bulbs and leveling systems that keep headlights aimed at the road—not into the eyes of oncoming drivers—even when weight in the trunk tilts your car upward.

Examples: Adaptive headlights are available on a wide range of high-end luxury and performance vehicles plus quite a few more affordable ones, such as the 2013 Mazda 3 and CX-5.

Verdict: This can be worth the money for drivers who do lots of nighttime driving on curvy roads that are not well-lit by streetlights.

Lane-departure warning/lane-assist systems use cameras to sense when your vehicle is drifting out of its lane. Lane-departure warning systems then sound an alarm or give some other signal to call your attention to the problem…while lane-assist systems apply brakes on one side to nudge the car back into the lane.

Examples: Lane-departure warning systems are fairly widely available. Lane assist is most common with luxury cars including Audi, Lexus and Mercedes, but it now is available in some mainstream vehicles, too, including the 2013 Ford Fusion and Explorer.

Verdict: Lane-assist and lane-departure systems could save your life if you drive when you are drowsy or distracted (though the better solution is to not drive while drowsy and to avoid distractions). These systems tend to work best on multilane highways and are less effective on country roads that lack painted outer lines. Some drivers find it annoying that when these systems are engaged, drivers must use their blinkers before changing lanes, even if they are the only ones on the road—if the blinker isn’t used, the system interprets the lane change as drifting.

Related: Mercedes Attention Assist monitors drivers for signs of fatigue and suggests stopping for a rest when prudent. It’s standard on many Mercedes models and useful for people who do lots of night driving. A new Cadillac system on the ATS and XTS sedans and SRX crossover is a variation on this. It vibrates the seat cushion when you drift out of the lane to startle you back into paying attention—but the jury still is out on this method.

Blind-spot detection provides a warning noise or light when there’s a vehicle in your blind spots—the areas slightly behind and to the side of your car that cannot easily be seen in your mirrors. Some blind-spot detection systems gently apply the brakes on one side to avoid a collision with a vehicle in your blind spot.

Example:Infiniti’s Blind Spot Intervention System will pull your vehicle away from a vehicle in your blind spot if it senses that you’re about to collide with that vehicle.

Verdict: Blind-spot warning systems have some value, but only if you often drive on multilane roads in moderate or light traffic. When traffic is heavy, these systems sound warnings so often that they’re more of an annoyance than a safety feature. These systems should not be considered a substitute for turning one’s head to check blind spots. And it’s not clear that these systems are that much more effective than simply aiming a vehicle’s mirrors properly—you should barely be able to see the sides of your own vehicle in your side mirrors—and adding an inexpensive aftermarket stick-on blind-spot convex mirror, available in any auto-parts store.

Forward collision warnings/brake support systems sound warnings when they sense that you’re about to hit something. They also might precharge the brakes to make them extra responsive in an emergency stop. Some even feature self-braking systems that apply the brakes on their own if the driver fails to do so. These self-braking systems generally are capable of avoiding collisions only when traveling below 20 to 25 miles per hour (mph), but they can reduce the vehicle’s speed at impact, tighten seat belts and take other steps to increase safety during higher-speed crashes.

Examples:The Volvo City Safety system…Mercedes-Benz Distronic Plus with Pre-Safe Brake system…and Acura Collision Mitigation Braking System are available on select models.

Verdict: It works. Research by the Highway Loss Data Institute found that vehicles equipped with forward collision avoidance systems are 14% less likely to get into accidents. Edmunds tested the Volvo City Safety system extensively and also concluded that it legitimately helps prevent rear-end collisions.

Night vision uses an infrared camera to display a real-time image of the road ahead onto a screen on the dash or center console. This infrared camera can detect dangers that are very difficult to spot in the dark or fog.

Examples:BMW Night Vision…Mercedes Night View Assist.

Verdict: The infrared images look cool, but this feature is not tremendously useful. Drivers generally are better off keeping their eyes on the road, not a display screen. Night vision could be useful for people who drive on roads where deer often dart unexpectedly out of the darkness, however.

Seat belt airbags inflate in accidents, distributing the impact of the belt across the torso.

Example:Ford now offers inflatable rear-seat seat belts as an option in certain models.

Verdict: These do provide some safety advantages in crashes, but they’re noticeably thicker and less comfortable than standard seat belts. That could create a dramatic reduction in safety if it discourages passengers from wearing their seat belts at all. Test inflatable belts for comfort before buying.


Many auto accidents occur while parking or backing out of parking spots. Backup cameras, now common, are no longer the only safety technology that can assist with this…

Around-view cameras compile feeds from a network of cameras arrayed around the perimeter of the vehicle to display a composite bird’s-eye view of the vehicle on a dash or center-console monitor during low-speed operation. It’s as if you have a camera above your vehicle pointed down.

Examples:Around View is available in many Infiniti and select Nissan models.

Verdict: This could be worth having if you often park in tight parking spaces.

Cross-traffic alert scans to the sides as you back out of a parking space and warns of approaching traffic.

Examples:Available on select 2013 Ford and Lincoln vehicles.

Verdict: This can be very useful for those who often must back out of tight parking spaces or obstructed-view driveways into traffic.

Source: Dan Edmunds, director of vehicle testing for automotive information provider Edmunds, Inc. He previously worked as a vehicle evaluation engineer for Toyota and Hyundai/Kia. Based in Santa Monica, California, the company has been providing information on new and used cars since 1966. Its Web site gets about 18 million visitors a month.