April 2008
SUVs and pickup trucks: Critical safety concerns
What to consider when buying your next vehicle
CRASH CONFORMITY Many new SUVs are being designed with lower bumpers for improved compatibility with cars.
Safety should be a key consideration when buying any vehicle, but it's not very easy to assess on your own. Some buyers think
they need a large vehicle, like an SUV or a pickup, to protect them in the event of an accident. Others worry about the higher
incidence of rollover accidents involving pickup trucks and SUVs.
In fact, there are several factors to think about when weighing the overall safety of a vehicle. We'll highlight the various issues you should consider and tell you where to find additional information.
Crash protection
The insurance industry and the federal government each perform several tests to simulate how a vehicle would perform in a real crash. The Insurance Institute for Highway Safety (IIHS) tests vehicles in an offset frontal crash at 40 mph, a more common type of head-on collision. In this test, only the portion of the vehicle in front of the driver hits a barrier. It challenges the car's structural integrity and its ability to protect the area around the driver without collapsing. IIHS rates vehicles good, acceptable, marginal, and poor.
The National Highway Traffic Safety Administration (NHTSA) crashes vehicles head-on into a solid wall at 35 miles per hour. This tests how well the car's safety belts and air bags protect occupants. The agency performs this test with most of the vehicles on the market and rates them on a scale of one to five stars.
The Insurance Institute conducts side-crash tests that are more severe than NHTSA's. It simulates a passenger car being hit in the side by a typical pickup truck or SUV at 31 miles per hour. Results are available at www.hwysafety.org .
NHTSA assigns star ratings to cars based on a side crash at 34 miles per hour to a moving vehicle at 17 miles per hour, and the impact occurs at a lower section than in the IIHS test. Its safety ratings are available at www.safercar.gov.
Cars with side-curtain air bags that cover the windows and protect a passenger's head have consistently been the best performers in both side-crash tests.
Vehicle compatibility
In a crash, the higher bumper on many taller vehicles, such as SUVs and trucks, hits a typical passenger car above the bumper line and crumple zone, exerting its force into weaker portions of the smaller vehicle and inflicting greater damage to the car and its occupants. To help reduce this incompatibility, many SUVs are being redesigned with lower bumpers. Automakers recently announced voluntary plans to design SUVs and pickup trucks in other ways that will make them less dangerous to passengers in smaller vehicles. The changes will include lower ride heights and reduced weight.
Rollover resistance
Perhaps the SUV safety issue that has garnered the most attention is rollover. The NHTSA says SUVs have a rollover rate that is three times that of passenger cars. The agency provides rollover ratings for SUVs and other vehicles at www.safercar.gov. It looks at two factors to determine how likely it is that an SUV will roll over in an accident.
The first thing it considers is called the static stability factor (SSF), which compares a vehicle's track width with its center of gravity. The numbers range from about 1.0 for an SUV to 1.5 for a sports car. The other is the Road Edge Recovery test, a quick left-right turn that simulates a driver over correcting the steering in an emergency. A vehicle that tips onto two wheels in the test has a greater chance of rolling over. Consumer Reports does not recommend any vehicle that tips up in this test.
NHTSA rates vehicles from one to five stars based on the combined test results. One star indicates a rollover risk of 40 percent or more in a single-vehicle accident. Five stars indicate a risk of 10 percent or less.
The agency's rollover ratings for vehicles in the dynamic test ranged from a low risk of 12 percent for the Nissan Quest to a 26 percent chance for the Ford Ranger 4WD. SUVs ranged from 14 to 27 percent; pickups from 14 to 26 percent; and minivans from 12 to 20 percent. Passenger cars ranged from 7 to 18 percent.
Rollover resistance is mainly a matter of physics. For a given track width, a taller vehicle has a higher center of gravity, which makes it more top-heavy than one that sits lower. Vehicle design, including suspension and tires, affects stability. In a situation where a vehicle is subjected to strong sideway forces, as in a sudden cornering maneuver, it's easier for a taller vehicle to roll over. During normal circumstances drivers rarely encounter such strong forces, but an emergency can happen without warning. A rollover can occur in several types of situations, such as during an accident-avoidance maneuver, taking a corner too fast for road conditions, or when a tire blows out.
A few SUVs, notably those made by Ford and Volvo, also use technology that can sense a rollover and inflate side-curtain air bags as it starts. This is designed to protect occupants from ejection.
Roof crush
One of the main reasons vehicle occupants are injured or killed in rollover accidents is that the roof collapses or deforms enough to cause a head injury. So every new vehicle, including SUVs and trucks, must pass NHTSA's roof-crush requirement.
In tests, a metal plate is pressed down against the roof at an angle. Under the current law, the roof cannot crush in more than five inches when the plate is pressed down with a force equal to 1.5 times the vehicle's weight.
NHTSA has proposed a new regulation that would increase the force roofs must withstand to 2.5 times the vehicle weight. Yet some safety advocates say that neither the current standard nor the new proposal is strong enough to protect vehicle occupants. The agency states that more than 60 percent of the vehicles it has tested currently meet the improved standard. But Joan Claybrook, president of the consumer advocacy group Public Citizen, says the new standard should require roofs to withstand at least 3.5 times the vehicle's weight.
Blind zones
The height of SUVs and pickup trucks creates large blind zones below the rear window and in front of the hood. According to Kids and Cars, which works to improve child safety, some 90 children die each year when drivers, sometimes parents, back over them while they are in blind zones. CR measures the blind zones of every vehicle we test. (See our report on vehicle blind spots). To check the size of a vehicle's blind zone, sit in the driver's seat while a friend standing behind the car holds a hand about waist level. Have the person walk back until you can see the hand through the rear window. This distance indicates how large the blind zone really is.
Some SUVs and minivans are now available with rear-view video cameras. Our testing has shown that when used regularly, they can be effective.
In fact, there are several factors to think about when weighing the overall safety of a vehicle. We'll highlight the various issues you should consider and tell you where to find additional information.
Crash protection
The insurance industry and the federal government each perform several tests to simulate how a vehicle would perform in a real crash. The Insurance Institute for Highway Safety (IIHS) tests vehicles in an offset frontal crash at 40 mph, a more common type of head-on collision. In this test, only the portion of the vehicle in front of the driver hits a barrier. It challenges the car's structural integrity and its ability to protect the area around the driver without collapsing. IIHS rates vehicles good, acceptable, marginal, and poor.
The National Highway Traffic Safety Administration (NHTSA) crashes vehicles head-on into a solid wall at 35 miles per hour. This tests how well the car's safety belts and air bags protect occupants. The agency performs this test with most of the vehicles on the market and rates them on a scale of one to five stars.
The Insurance Institute conducts side-crash tests that are more severe than NHTSA's. It simulates a passenger car being hit in the side by a typical pickup truck or SUV at 31 miles per hour. Results are available at www.hwysafety.org .
NHTSA assigns star ratings to cars based on a side crash at 34 miles per hour to a moving vehicle at 17 miles per hour, and the impact occurs at a lower section than in the IIHS test. Its safety ratings are available at www.safercar.gov.
Cars with side-curtain air bags that cover the windows and protect a passenger's head have consistently been the best performers in both side-crash tests.
Vehicle compatibility
In a crash, the higher bumper on many taller vehicles, such as SUVs and trucks, hits a typical passenger car above the bumper line and crumple zone, exerting its force into weaker portions of the smaller vehicle and inflicting greater damage to the car and its occupants. To help reduce this incompatibility, many SUVs are being redesigned with lower bumpers. Automakers recently announced voluntary plans to design SUVs and pickup trucks in other ways that will make them less dangerous to passengers in smaller vehicles. The changes will include lower ride heights and reduced weight.
Rollover resistance
Perhaps the SUV safety issue that has garnered the most attention is rollover. The NHTSA says SUVs have a rollover rate that is three times that of passenger cars. The agency provides rollover ratings for SUVs and other vehicles at www.safercar.gov. It looks at two factors to determine how likely it is that an SUV will roll over in an accident.
The first thing it considers is called the static stability factor (SSF), which compares a vehicle's track width with its center of gravity. The numbers range from about 1.0 for an SUV to 1.5 for a sports car. The other is the Road Edge Recovery test, a quick left-right turn that simulates a driver over correcting the steering in an emergency. A vehicle that tips onto two wheels in the test has a greater chance of rolling over. Consumer Reports does not recommend any vehicle that tips up in this test.
NHTSA rates vehicles from one to five stars based on the combined test results. One star indicates a rollover risk of 40 percent or more in a single-vehicle accident. Five stars indicate a risk of 10 percent or less.
The agency's rollover ratings for vehicles in the dynamic test ranged from a low risk of 12 percent for the Nissan Quest to a 26 percent chance for the Ford Ranger 4WD. SUVs ranged from 14 to 27 percent; pickups from 14 to 26 percent; and minivans from 12 to 20 percent. Passenger cars ranged from 7 to 18 percent.
Rollover resistance is mainly a matter of physics. For a given track width, a taller vehicle has a higher center of gravity, which makes it more top-heavy than one that sits lower. Vehicle design, including suspension and tires, affects stability. In a situation where a vehicle is subjected to strong sideway forces, as in a sudden cornering maneuver, it's easier for a taller vehicle to roll over. During normal circumstances drivers rarely encounter such strong forces, but an emergency can happen without warning. A rollover can occur in several types of situations, such as during an accident-avoidance maneuver, taking a corner too fast for road conditions, or when a tire blows out.
A few SUVs, notably those made by Ford and Volvo, also use technology that can sense a rollover and inflate side-curtain air bags as it starts. This is designed to protect occupants from ejection.
Roof crush
One of the main reasons vehicle occupants are injured or killed in rollover accidents is that the roof collapses or deforms enough to cause a head injury. So every new vehicle, including SUVs and trucks, must pass NHTSA's roof-crush requirement.
In tests, a metal plate is pressed down against the roof at an angle. Under the current law, the roof cannot crush in more than five inches when the plate is pressed down with a force equal to 1.5 times the vehicle's weight.
NHTSA has proposed a new regulation that would increase the force roofs must withstand to 2.5 times the vehicle weight. Yet some safety advocates say that neither the current standard nor the new proposal is strong enough to protect vehicle occupants. The agency states that more than 60 percent of the vehicles it has tested currently meet the improved standard. But Joan Claybrook, president of the consumer advocacy group Public Citizen, says the new standard should require roofs to withstand at least 3.5 times the vehicle's weight.
Blind zones
The height of SUVs and pickup trucks creates large blind zones below the rear window and in front of the hood. According to Kids and Cars, which works to improve child safety, some 90 children die each year when drivers, sometimes parents, back over them while they are in blind zones. CR measures the blind zones of every vehicle we test. (See our report on vehicle blind spots). To check the size of a vehicle's blind zone, sit in the driver's seat while a friend standing behind the car holds a hand about waist level. Have the person walk back until you can see the hand through the rear window. This distance indicates how large the blind zone really is.
Some SUVs and minivans are now available with rear-view video cameras. Our testing has shown that when used regularly, they can be effective.
