SUVs and Safety

SUV safety, once a key concern for the segment when it was booming in the 1990s, has made real strides in recent years, and crash testing by the National Highway Traffic Safety Administration and the Insurance Institute for Highway Safety is proving increasingly indicative of real-world performance.

When judging crash tests, Cars.com by far favors the IIHS results because they are closer to real-world crashes. "It has taken [10 years] to accumulate enough real-world crash fatality data to make the comparisons between crash-test ratings and experience in real crashes," said Adrian Lund, IIHS chief operating officer. "What we've found is that the tests are very good predictors of fatality risk."

Though weight is a factor in collisions, it isn't the only one. Typically, a heavier vehicle fares better in a crash with a smaller one, but the truck-based vehicles that spawned the SUV revolution didn't have the crash protection built into them that common unibody cars did. Body-on-frame trucks were built to be tough, not to absorb crash energy by using approaches like crumple zones. They also had high centers of gravity and were tippy compared to other vehicles.

Fortunately, as automakers have incorporated crumple zones into their truck-based models, SUVs are earning much-improved crash-test ratings. Also, unlike early-generation SUVs, the new and completely redesigned truck-based models of the past few years are being built with wider tracks (the distance between the left and right wheels), lowered bodies and/or other measures to lower their center of gravity.

Most crossovers — often called car-based SUVs, regardless of their size — are even more grounded. Of the 2010 SUVs and crossovers rated by NHTSA as of this publication, there are only three car-based models with rollover ratings of three stars instead of four (five is best): the Honda Element, the Kia Sportage (front-wheel drive model) and the Ford Escape (plus its sister models, the Mercury Mariner and Mazda Tribute). Thankfully all three have standard electronic stability systems. The Element, Escape and its siblings are designated Top Safety Picks by IIHS because of Good scores in frontal, side- and rear-impact crash tests. The Sportage is less impressive, with only Acceptable ratings in the frontal and side-impact tests. All other three-star rated 2010 SUVs are the heavier-duty, truck-based type.

There are some truck-based SUVs rated at four stars: the Jeep Wrangler Unlimited (four-door version only), Kia Borrego, Mercedes-Benz ML-Class and the hulking Toyota Sequoia. Four-wheel-drive versions of the Ford Expedition and Lincoln Navigator also rate four stars, but the rear-wheel drive models get three stars. No SUV has a five-star rollover rating.

Safety Features for SUVs

The Chevrolet Tahoe is one of several SUVs to feature a standard electronic stability system.

Some desirable safety features for SUVs and crossovers are the same as those for any vehicle: antilock brakes, three-point (lap-and-shoulder) seat belts and head restraints in all seating positions, multistage frontal airbags, and occupant classification in the front passenger seat, which determines the occupant's weight (and thus size) and fires the airbag at one of two or more levels of intensity.

There are three features that are especially useful in SUVs and crossovers, and one you should avoid, if safety is a concern:

1. Electronic stability systems: Sold under names like ESP, StabiliTrak, DSTC, VSC, VDC — and the list goes on — electronic stability systems can limit acceleration and apply any of the antilock brakes to keep you on course if you start to go out of control. It doesn't prevent a rollover, but it's quite effective at preventing conditions that can lead to one. For this reason, the industry was already on its way toward making the feature standard equipment on SUVs when NHTSA announced it would be required on all cars and light trucks by the 2012 model year.

What to look for: Don't confuse this feature with simple traction control (also sold under acronym names), which only prevents wheelspin upon acceleration. Be positive that an electronic stability system is what you're getting.

2. Side curtain airbags: This type of airbag deploys downward from the ceiling to cover some or all side windows upon side impact. One could argue that this type of airbag is less important on taller vehicles because other tall vehicles are likely to strike your SUV's door sills or doors, which are built to absorb energy. (A car, on the other hand, would have only windows and narrow pillars to protect its occupants from a collision with a truck.) But side curtain airbags in some models can serve another purpose: In the event of a rollover, they protect occupants and help keep them inside the vehicle, staying inflated long enough for several rolls. Occupant ejection — not roof crush strength — is the main cause of deaths in rollover accidents.

What to look for: Just having side curtain airbags isn't enough. Make sure they're designed to deploy in a rollover. Also favor systems that cover all rows of seats. Not all three-row vehicles have protection for the third row.

3. Rollover prevention: Something of a holy grail among SUV safety features, a rollover prevention or avoidance system actually senses an impending rollover and triggers the electronic stability system to forestall it. (Stability systems alone can only diminish the chance of tipping up on two wheels to begin with.) The Volvo XC90 was the first vehicle to offer this feature, which the automaker calls Roll Stability Control. Volvo is a division of Ford, and the RSC system has spread to other Ford vehicles, including the Lincoln Navigator. It is still available on some models from Land Rover, which Ford owned until 2008.

What to look for: Check our model reports to find which Ford, Mercury, Lincoln and Land Rover products offer RSC.

4. Wheel and tire "upgrades": This is the feature you should avoid if you care about safety and rollover prevention. This will be unpopular with style-conscious buyers, but it has to be said: An increasing number of vehicle owners are customizing their vehicles (wheels and tires being the most common upgrade) in complete ignorance of the effects on safety. To put it plainly, vehicles are designed to work as a system. Change any part and there are consequences. Wheel and tire combinations that are larger, heavier and/or have greater traction are likely to diminish an SUV's safety. Larger diameters foil antilock brakes and stability systems and can compromise braking. Heavier weight affects the suspension's ability to keep the tire on the road and again affects braking. Tires with greater grip can increase the chance of rollover. If that doesn't convince you, bear in mind that the manufacturer has little or no responsibility for your safety if you've modified the vehicle mechanically. In short, your next of kin would have a tough time in court.

What to look for: If you must customize your vehicle, your best bet is not to go to extremes. Keep the outside diameter of the tire the same, don't increase the wheel diameter too much and think twice about putting significantly different tires on your ride. Believe it or not, the people who engineered your vehicle — as a unit — really know what they're doing.

Protecting Those Outside Your Vehicle

The Honda Pilot is a SUV that has a "park assist" feature to warn drivers when they are getting close to an object while they are parking the vehicle.

While SUVs and crossovers are getting better at protecting their occupants, there's also the issue of protecting the occupants of the smaller vehicles with which they might collide. Aside from the weight issue, it's a matter of angles: A truck can ride up over the most robust part of a car's frame structure, bypassing its crumple zone and plowing into its cabin. Thankfully, there's evidence that SUVs are becoming less deadly in this regard. Many manufacturers have worked since 2003 to make SUVs more compatible in crashes with smaller vehicles by lowering their frames to engage a car's crumple zones.

IIHS cross-referenced a list of such SUVs with fatality data from the past few years and found that the fatality risk for a belted car driver was as much as 21 percent lower when crashing head-on with a compatible SUV than with a conventional one. (There's practically no change for unbelted drivers.) The side-impact results are more dramatic: a nearly 50 percent decline in car occupant fatality risk when hit by a compliant SUV.

There are also features that can help protect pedestrians behind vehicles — a significant problem in SUVs that sit high and have large blind spots. One is sonar-based "park assist" that sounds beeps of increasing frequency as the rear bumper nears an obstacle or person. A newer feature, the backup camera, shows a wide-angle view behind the vehicle on a screen when the vehicle's transmission is in Reverse. This feature mainly comes along with expensive optional navigation systems in vehicles such as the Honda Pilot and Lexus RX 350, but in the past year the feature has proliferated as a stand-alone option with separate, smaller displays in dashboards and rearview mirrors.

Young Drivers and SUVs

Speaking generally, SUVs aren't the best choice for young or inexperienced drivers. The threat of rollovers still looms, and combine that with the fact that single-vehicle accidents are most common among young drivers, and you can see the danger. The lesson that too few drivers learn is that trucks don't handle or stop like cars do. They're generally not as nimble, and they don't stop as quickly. A young driver who takes a freeway offramp at 50 mph in a sports car might continue unscathed. One who does the same in a family sedan might slide off into the weeds or something less forgiving. One who tries it in an SUV is likely to roll over. Simply put, SUVs are best for drivers who have more self-control than teenagers do.