IIHS Test Doesn’t Bode Well for Smaller Cars

Most small car designs earned poor ratings in side impact crash tests recently conducted by the Insurance Institute for Highway Safety.

Only the Chevrolet Cobalt and Toyota Corolla, both equipped with optional side airbags with head protection, performed well enough to earn the Institute’s second highest rating of acceptable. Without the optional airbags, the Cobalt and Corolla are rated poor for side impact protection. The test represents what happens when a passenger vehicle is struck in the side by a pickup truck or SUV.

Another 12 small cars also earned poor ratings: Dodge Neon, Ford Focus, Hyundai Elantra, Kia Spectra, Mazda 3, Mitsubishi Lancer, Nissan Sentra, Saturn ION (tested with and without side airbags), Suzuki Forenza, Suzuki Aerio, and Volkswagen New Beetle.

Three more small cars will be tested in side impacts later this year. The Mini Cooper and Subaru Impreza will have new design features that are intended to improve side impact protection. The Honda Civic will be a completely redesigned model.

“These side impact results are similar to the results in 1997 when the Institute first rated small cars in the frontal offset crash test,” says Institute chief operating officer Adrian Lund. “Back then, no small car earned a good frontal crash test rating. Now almost every small car earns a good rating in the frontal test. As manufacturers redesign their vehicles, we expect that small cars will get better in the side impact test too.”

In the Institute’s side impact test, a moving deformable barrier strikes the driver side of a passenger vehicle at 31 mph. The barrier weighs 3,300 pounds and has a front end that is shaped to simulate the front end of a typical pickup or SUV. In each side-struck vehicle are two instrumented dummies the size of a small (5th percentile) woman, one positioned in the driver seat and one in the rear seat behind the driver.

New frontal test results: The Institute also conducted frontal offset crash tests of the Cobalt and Spectra. The Cobalt was tested because it’s a new design. Kia requested the test of the Spectra after modifying the design of the airbag system. Before this change, the Spectra was rated poor in the frontal test.

In the frontal offset test, the vehicle strikes a deformable barrier at 40 mph. The vehicle is offset, so only 40 percent of the front end strikes the barrier on the driver side. In offset tests a smaller area of the front end must manage the crash energy, compared with full-width tests. Injury measures are taken from a dummy representing an average-size male (50th percentile) positioned in the driver seat.

Cobalt and Corolla are acceptable with side airbags: Side curtain-style airbags designed to protect the heads of front- and rear-seat occupants are optional on these vehicles (front seat-mounted torso airbags are included with the airbag option on the Corolla). When side airbags are optional, the Institute tests without the option and will conduct a second test with the optional airbags if the manufacturer requests it and reimburses the Institute for the cost of the vehicle. General Motors requested second tests of the Cobalt and Saturn ION. Toyota requested a second test of the Corolla.

“With the curtain airbags the heads of the dummies in the front and rear seats of the Cobalt and Corolla were cushioned, and head injury measures were low,” said Lund. “Head injuries are a factor in many deaths in real-world side impact crashes, and side airbags designed to protect the head make a big difference.”

In the Cobalt, forces on the driver dummy’s torso indicated the possibility of rib fractures or internal organ injuries. In the Corolla, there was the possibility of a fractured pelvis. Protection for the rear passenger was good in both cars.

“GM and Toyota still need to beef up the side structures to improve their side impact ratings from acceptable to good,” said Lund.

In the Institute’s frontal offset test, the Cobalt and Corolla are rated good and “best picks.” The Cobalt’s seat/head restraints are rated good based on a test that simulates a rear impact, and the Corolla’s are poor. Taken together with ratings in the side impact test, the Cobalt and Corolla equipped with optional side airbags now are the highest rated small cars overall in the Institute’s crashworthiness ratings.

Neon is worst performer: The Neon has “major problems beginning with its structure. This car is a disaster,” according to Lund. “The structure is poor, and both dummies’ heads were hit by the barrier during the crash test. High forces were recorded on the head, torso, and pelvis of the driver dummy. If this had been a real driver in a real crash, it’s likely it wouldn’t have been survivable.”

While combination head and torso side airbags for the front occupants are available on the Neon, DaimlerChrysler did not ask for a second test with the airbags.

“With a poor structure, the company probably didn’t think side airbags would make a big difference in the Neon’s performance,” said Lund. Pointing to the Neon’s marginal rating in the Institute’s frontal test, he adds that “if safety is a priority, the Neon is a small car to be avoided.”

Vehicles need good structure as well as side airbags: Four of the vehicles that earned poor side crashworthiness ratings (Elantra, Forenza, New Beetle, and Spectra) are equipped with standard side airbags with head protection. These cars are rated good or acceptable for head injury measures recorded on the driver dummies. The Saturn ION with optional side airbags also earned an acceptable rating for driver head injury. However, the structures of all of these vehicles allowed too much intrusion during the test. Forces recorded on the driver dummies’ torsos and/or pelvic areas were high.

“Side airbags can protect the head, but if the vehicle structure doesn’t hold up well then serious injuries to other body regions still can occur,” said Lund. “With better structures along with the side airbags, the performances of these vehicles would improve.”

Side airbags are reducing risks in real-world crashes: Institute research shows that side airbags with head protection are reducing deaths by about 45 percent among drivers of cars struck on the driver side. Before the availability of head-protecting airbags, there was virtually nothing to prevent people’s heads from being struck by intruding vehicles or rigid objects like trees or poles in serious side impacts. Side airbags that protect the chest and abdomen, but not the head, also are reducing deaths but are less effective (about a 10 percent reduction in deaths). Plus well-designed doors with appropriate padding can provide good protection for the chest and abdomen.

Head-protecting airbags are necessary for effective side impact protection, but torso airbags are not. For example, the Corolla the Institute tested was equipped with torso airbags. The Cobalt wasn’t. Both had head-protecting curtain airbags. Both earned acceptable ratings.

Cobalt is ‘best pick’ in frontal test: This is General Motors’ new entry in the small car category. It’s a big improvement over the Chevrolet Cavalier, which still is being sold. The Cavalier is rated poor for frontal crashworthiness.

“The Cobalt’s structure held together very well in the frontal test,” said Lund. The driver’s survival space was maintained, and there was minimal to moderate intrusion into the footwell area. The dummy’s movement was well controlled during the crash, and all injury measures were low. The Cobalt is rated good and earned the added designation of “best pick.”

Spectra’s frontal crash performance improves: When the Institute tested the Kia Spectra last year, it was the first vehicle since 2001 to earn a poor rating in the frontal test. Among other factors, forces on the dummy’s head were high when it bottomed out the airbag and then struck the door frame. Kia redesigned the driver airbag and asked the Institute to test the Spectra again.

“In this new test, the Spectra’s performance was better but not improved enough to earn a good rating,” Lund pointed out. “Another high head acceleration occurred when the dummy’s head bottomed out the airbag but, overall, injury measures were lower, dummy movement was somewhat better controlled, and the Spectra moves from a poor rating to acceptable” (the improved rating applies to Spectras built after January 2005).

How vehicles are evaluated in the side impact test: Each vehicle’s overall side evaluation is based on injury measures recorded on two instrumented SID-IIs dummies, assessment of head protection countermeasures, and the vehicle’s structural performance during the impact. Injury measures obtained from the two dummies, one in the driver seat and the other in the rear seat behind the driver, are used to determine the likelihood that the driver and/or passenger would have sustained serious injury to various body regions. The movements and contacts of the dummies’ heads during the crash also are evaluated. This assessment is more important for seating positions without head-protecting airbags which, assuming they perform as intended, should prevent injurious head contacts. Structural performance is based on measurements indicating the amount of B-pillar intrusion into the occupant compartment. Some intrusion into the compartment is inevitable in serious side impacts, but any intrusion that does occur should be uniform both horizontally and vertically and shouldn’t seriously compromise the driver or passenger space.

Institute’s frontal test complements government test: Each vehicle’s overall frontal evaluation is based on results of a 40 mph frontal offset test into a deformable barrier. The evaluation is based on three aspects of performance — measurements of intrusion into the occupant compartment, 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.