Crossovers, SUVs and Safety
By By Joe Wiesenfelder, Cars.com
Cars.com can't designate a vehicle as safe or unsafe. What we can do is interpret crash-test and rollover ratings and provide a guide to safety features. For what it's worth, crash tests are increasingly proving indicative of real-world performance.
The two third-party agencies that perform the tests are the federal government's National Highway Traffic Safety Administration and the Insurance Institute for Highway Safety, a nonprofit organization funded by the insurance industry. Cars.com by far favors the IIHS results because they are closer to real-world crashes, as explained in our Guide to Crash Tests and Rollover Ratings. "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. All other things being equal, a heavier vehicle will fare better in a crash with a smaller one. But all other things are never equal. The truck-based vehicles that spawned the SUV revolution had nowhere near the crash protection built into them as did the common unibody car. Body-on-frame trucks were built to be tough, not to absorb crash energy by means of crumple zones. They also had high centers of gravity and were tipsy compared to other vehicle types.
Ironically, now that SUV safety has come under greater scrutiny and NHTSA has issued rollover ratings, two of the biggest safety issues have started to fade on their own. First, automakers have begun to incorporate crumple zones into their truck-based SUVs, which are earning much-improved crash-test ratings. Second, 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 car-based SUVs and crossovers are even more grounded: Of all the 2009 SUVs rated by NHTSA as of this publication, there are only two car-based models with rollover ratings of three stars instead of four (five is best): the Honda Element and the Ford Escape (plus its sister models, the Mercury Mariner and Mazda Tribute). Thankfully they both include standard electronic stability systems and are now designated Top Safety Picks by IIHS thanks to Good scores in frontal-, side- and rear-impact crash tests. All other three-star SUVs are the heavier-duty, truck-based type.
The Chevrolet TrailBlazer was one of a few truck-based SUVs to get four stars in NHTSA's rollover test.
The Chevrolet TrailBlazer was one of a few truck-based SUVs to get four stars in NHTSA's rollover test.
There are some trucks rated at four stars: The Chevrolet TrailBlazer (and its GMC Envoy and Saab 9-7x sister models), Chrysler Aspen (and Dodge Durango), Ford Expedition (and Lincoln Navigator), Jeep Grand Cherokee, Kia Sorento, Toyota Sequoia and Mercedes-Benz ML-Class. Though they're heavy-duty off-roaders, the Jeep and Mercedes technically are car-based, which might explain their advantage. No SUV has a five-star rollover rating.
Safety Features for SUVs
Some desirable safety features for SUVs 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 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 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. Don't mess around. 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 of the 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 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: They protect occupants and help keep them inside the vehicle in the event of a rollover. They stay inflated long enough for several rolls.
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 seat rows. 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 Motor Co., and the RSC system has spread to other Ford vehicles, including the Lincoln Navigator. Ford offered to license this feature to other manufacturers, but none has taken them up on it. Instead, some competing automakers have devised systems that are claimed to sense likely rollovers before any wheels leave the ground, and to activate their associated stability systems.
What to look for: Check our model reports to find which Ford, Land Rover, Lincoln and Mercury 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 its effect on safety. To put it plainly, vehicles are designed to work as a system. Change any part and you change multiple characteristics. 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 may 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
While SUVs are getting better at protecting their occupants, there's also the issue of protecting occupants of smaller vehicles with which they might collide. Aside from the weight issue, it's a matter of compatibility: A high 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 18-21 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 47-49 percent decrease 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 perspective behind the vehicle on a dashboard LCD 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 Toyota is now offering it as a stand-alone option with its own, smaller dashboard display in the 2009 Highlander.
Young Drivers and SUVs
Speaking generally, SUVs aren't the best choice for a young or inexperienced driver. Rollovers still loom, and most are single-vehicle accidents. Combine that with the fact that single-vehicle accidents are most common among young drivers, and you can see the danger. The lesson not enough drivers learn is that trucks don't handle or stop like cars. They're generally not as nimble, and they don't stop as short. 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 teens, as a rule, do.
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