ARLINGTON, Va. — In frontal offset crash tests conducted recently by the Insurance Institute for Highway Safety, eight new or redesigned midsize SUVs earned ratings of good, and one is acceptable. Three luxury models (Lexus RX 330, Infiniti FX, and Cadillac SRX) earned good ratings overall and the added designation of "best pick." Five other SUVs (Toyota 4Runner, Nissan Murano, Chrysler Pacifica, Honda Pilot, and Mitsubishi Endeavor) also earned good ratings, and all but the Endeavor are best picks. The Kia Sorento is rated acceptable (see attachment).
Vehicle ratings reflect performance in 40 mph frontal offset crash tests into a deformable barrier. Based on the results, the Institute evaluates the crashworthiness of passenger vehicles, assigning each vehicle a rating from good to poor overall. If a vehicle earns a good rating, it means that in a real-world crash of similar severity a belted driver would be likely to walk away without serious injuries.
"These results demonstrate the effectiveness of the Institute's frontal crash test program in bringing about improvements in vehicle designs," says Adrian Lund, the Institute's chief operating officer. "When the Institute first tested midsize SUVs in 1996, none was rated good. Now there are 16 current midsize SUV designs rated good." But Lund notes that "7 still are rated marginal or poor."
Toyota 4Runner is best performer
The redesigned 4Runner improved compared with the previous generation model that was rated acceptable when the Institute tested it in 1996. "The previous model had some intrusion into the footwell area, and the steering wheel moved upward too much during the crash, compromising the performance of the restraint system," Lund says. "In contrast, the new 4Runner is a good performer across the board with minimal intrusion into the passenger compartment, a steering column that doesn't move much, and low injury measures on the dummy. It's a good performer and a best pick."
Kia Sorento is only acceptable
While the structure of the Sorento held up well, the restraint system didn't do a good job of controlling the dummy's movement during the crash.
"Kia has room for improvement with the Sorento," Lund says. "The dummy's head hit the steering wheel through the airbag and also struck the door frame on rebound. Both hits were hard. Plus the driver's seat tipped toward the door, which compromises restraint system performance."
Honda and Infiniti are tested twice
In the first tests of the Pilot and the FX, the front airbags deployed late. As a result, the dummies recorded high head accelerations.
"The engineers at Honda and Nissan recognized that their airbag systems needed to be improved. They made changes to the software that controls airbag firing, and we retested both models. In the second tests, the airbags fired much earlier and the high head accelerations were eliminated. With the change, the Pilot and FX are good performers and best picks," Lund says. Both companies are conducting recalls to modify the airbag software on earlier models.
Structural design is key to good performance
The Institute's frontal offset test into a deformable barrier is especially demanding of vehicle structure. The driver side hits the barrier, so a relatively small area of the vehicle's front-end structure must manage the crash energy. This means intrusion into the occupant compartment is more likely to occur than in a full-width test.
"Good structural design is the key to good performance in the offset tests," Lund says. "If a vehicle's front-end structure absorbs and manages the crash energy so the occupant compartment remains largely intact, with little or no intrusion into the driver's space, then the dummy's movement can be controlled, and injury measures are likely to be low. In contrast, poor structural design means greater likelihood of poor control of the dummy and high injury measures."
Institute and government crash tests complement each other
The Institute's crashworthiness evaluations are based on results of frontal offset crash tests at 40 mph. Each vehicle's overall evaluation is based on three aspects of performance — measurements of occupant compartment intrusion, injury measures from a Hybrid III dummy positioned in the driver seat, and analysis of slow-motion film to assess how well the restraint system controlled dummy movement during the test.
The federal government has been testing new passenger vehicles in 35 mph full-front crash tests since 1978. This New Car Assessment Program has been a major contributor to crashworthiness improvements — in particular, improved restraint systems in new passenger vehicles. The Institute's offset tests, conducted since 1995, involve 40 percent of a vehicle's front end hitting a deformable barrier at 40 mph. This test complements the federal test involving the full width of the front end hitting a rigid barrier. Both tests are contributing to improvements in crashworthiness — in particular improved crumple zones and safety cages.
The same 40 mph offset crash test is used to evaluate new cars by the European Union in cooperation with motor clubs, by an Australian consortium of state governments and motor clubs, and by a government-affiliated organization in Japan.