ARLINGTON, Va. — For the first time, the Insurance Institute for Highway Safety has evaluated vehicles in side impact crash tests to provide consumer information. The best performers among the 12 small SUVs tested (2003 models) are the Subaru Forester and the Ford Escape with optional side airbags. In contrast, 7 other small SUVs earned the lowest rating of poor — the Escape without optional side airbags, Toyota RAV4, Suzuki Grand Vitara/Vitara/Chevrolet Tracker, Land Rover Freelander, Mitsubishi Outlander, Saturn VUE, and Honda Element. The Jeep Wrangler and Honda CR-V are rated marginal, and the Hyundai Santa Fe is acceptable (see Attachment 1 for comparative ratings).
The Institute’s side impact crash test represents what happens when a passenger vehicle is struck in the side by a pickup truck or SUV.
The Subaru Forester is the only one of the 12 small SUVs to earn a good rating in not only the side impact crashworthiness evaluation but also the Institute's frontal offset crash test.
The side impact test represents what happens when a passenger vehicle is struck in the side by a pickup truck or SUV at about 30 mph. The results of this test expand the Institute's testing programs for consumer information. For eight years the Institute has been providing comparative rankings of passenger vehicles based on performance in frontal offset crash tests at 40 mph. Now most new passenger vehicles are being designed to earn good ratings in this test.
"Our side impact crash test is severe," says Institute president Brian O'Neill. "Given the designs of today's vehicles, it's unlikely that people in real-world crashes as severe as this test would emerge uninjured. But with good side impact protection, people should be able to survive crashes of this severity without serious injuries."
O'Neill adds that he expects this new crashworthiness evaluation program to influence consumers' car-buying choices. "This is what happened with our frontal crash test results, and now we expect consumers will use the new test results to help them choose vehicles with good occupant protection in both front and side impacts."
Because consumers pay attention to the Institute's crash test results, automakers are expected to upgrade their vehicles' side impact protection, just as they've upgraded the protection their vehicles offer in frontal crashes.
"Ideally, passenger vehicles should be good performers in both tests — a double good," O'Neill says.
The configuration of the Institute's side impact test is a 31 mph perpendicular impact into the driver side of a passenger vehicle. The moving deformable barrier that strikes the test vehicle weighs 3,300 pounds and has a front end shaped to simulate the typical front end of a pickup or SUV. In each side-struck vehicle are two instrumented dummies, one in the driver seat and one in the rear seat behind the driver. These dummies are the size of a short (5th percentile) female or a 12-year-old child.
"This is the first U.S. consumer information test program to use a dummy that represents small females," O'Neill points out.
Forester is best performer and Outlander is worst
The side airbag in the Subaru Forester kept the injury measures recorded on the driver dummy relatively low. The dummy in the rear seat also recorded relatively low measures, although its head did hit the pillar behind the back door — an area required by federal standard to limit head impact forces. There was somewhat less intrusion into the Forester than into several of the other small SUVs the Institute tested.
In contrast, the Mitsubishi Outlander was the worst performer in the side impact test. There was more intrusion into the occupant compartment than in many of the other vehicles tested. The Outlander that was tested didn't have side airbags. The barrier struck the driver dummy's head, and the injury measures recorded on the head as well as on the torso and pelvis were very high.
Ford Escape with and without side airbags
Ford offers side airbags as optional equipment in the front seats of Escapes. The Institute tested Escapes with and without this option.
"There was a huge difference in the results," O'Neill says. "The driver dummy with the airbag to protect its head and torso recorded low injury measures, while high measures were recorded on the driver dummy in the Escape without side airbags. Even though the Escape with side airbags was a good performer in this test, it was only marginal in our frontal offset test."
Relative importance of side impacts
Today's passenger vehicles are more crashworthy than they used to be, especially in frontal crashes. As occupant protection in frontal crashes improves, the relative importance of protecting people in side impacts increases. From the early 1980s until 2000, car driver death rates decreased from 164 to 87 per million cars registered. This represents a 47 percent decline. Most of this improvement was in frontal crashes, in which driver death rates decreased from 86 to 41 per million (52 percent decline). The improvement was much smaller in side impacts — the death rate decreased from 42 to 32 per million (24 percent decline).
In crashes with another passenger vehicle, 51 percent of driver deaths in recent model cars during 2000-01 occurred in side impacts, up from 31 percent in 1980-81. During the same time, the proportion of deaths in frontal impacts declined from 61 percent to 43 percent (see Attachment 2, Table 1).
These changes are attributable to two effects. There have been significant improvements in frontal crash protection — standard airbags, improved structural designs, and higher belt use rates, for example. At the same time, growing sales of SUVs and pickups have exacerbated height mismatches among passenger vehicles, thereby increasing the risks to occupants of many vehicles struck in the side. Seventy-one percent of the driver deaths in cars struck on the driver side by other passenger vehicles during 1980-81 occurred when the other vehicle was a car. Twenty-nine percent occurred when the striking vehicle was a pickup or SUV. By 2000-01 these percentages had almost reversed — 57 percent of the driver deaths in cars struck on the driver side by another passenger vehicle involved striking SUVs or pickups, while 43 percent involved striking cars (see Attachment 2, Table 2).
Head injuries are a leading cause of occupant deaths in side impacts. For example, the 23-year-old driver of this car died when his head was struck by the intruding front end of a pickup truck. See Attachment 3 for more examples.
"The risks to people in a side-struck vehicle greatly increase if the striking vehicle rides higher off the ground than the struck vehicle. Thus, the risks are much higher when an SUV strikes the side of a car than when the striking vehicle is another car," O'Neill explains.
Head protection in side impacts
Almost 10,000 passenger vehicle occupants die each year in side impacts, and head injuries are a leading cause. Side airbags designed specifically to protect the head can reduce such deaths and the even more numerous nonfatal head injuries that occur in side impacts.
Both of the small SUVs with good overall ratings in the Institute's side impact test are equipped with side airbags designed to protect the heads of front-seat occupants. These are standard on the Subaru Forester and optional on the Ford Escape. The Hyundai Santa Fe, which also has standard side airbags with head protection, earned an acceptable rating. In contrast, none of the seven small SUVs with poor ratings is equipped with standard side airbags designed to protect the head.
(Note: The Saturn VUE does have an optional inflatable curtain, but when side airbags are optional the Institute tests vehicles without this option. If a manufacturer selling optional side airbags requests the Institute to conduct an additional test of a vehicle with this option and agrees to reimburse the cost of the vehicle, a second test is conducted. General Motors didn't request such a test for the VUE, but Ford did request a test of the Escape with optional side airbags. The Honda CR-V and Mitsubishi Outlander have optional side airbags to protect the thorax, but neither manufacturer requested a second test with this option.)
None of the small SUVs the Institute recently tested has side airbags to protect the heads of people riding in rear seats. (The VUE's optional head airbag system does cover the rear seating position. However, as noted above the Institute didn't test this vehicle.)
Availability of side airbags
More and more manufacturers are offering side airbags as standard or optional equipment, and some cars and larger SUVs are being equipped with newer inflatable curtains designed to protect rear-seat occupants' heads (see Attachment 4).
According to a recent J.D. Power survey of 50,000 people, 34 percent said they "definitely want" side airbags, up from 18 percent in 1997 (2002 Feature Contenting Report). Another J.D. Power survey reveals side airbags at the top of the list of 19 vehicle features respondents said they want. Still, reported sales of optional side airbags are low.
Institute versus federal side impact crash test
Since 1997 the federal New Car Assessment Program, which compares crashworthiness among new passenger vehicles, has included side impacts. In these tests, an impactor with a deformable front end representing the front of a car is used to strike the sides of the vehicles being assessed. This moving deformable barrier was developed in the early 1980s, when cars represented most of the vehicles on the road. The height of the barrier's front end is below the heads of the dummies that measure injury risks in the side-struck vehicles. These federal tests don't assess the risks of head injury from impacts with vehicles like SUVs and pickups.
The changed vehicle mix and high risks to occupants of side-struck vehicles when the striking vehicles are SUVs or pickups led the Institute to modify the moving deformable barrier used in the federal test so the front end represents the geometry of a typical SUV or pickup. The result is a barrier that's higher off the ground, taller, and contoured. The design of this barrier and choice of the test speed (31 mph) reflect extensive developmental tests, including tests comparing the results from side impacts with barriers versus side impacts with SUVs and pickups.
Federal moving deformable barrier
IIHS moving deformable barrier
Another difference between Institute and federal side impact tests involves the choice of test dummies. The Institute uses SID-IIs dummies, which are smaller than the dummy (SID) used in the federal government's tests. SID-IIs is a newer design than SID, which was developed in the 1970s, and it records more injury measures across more body regions.
SID-IIs represents a small (5th percentile) female or a 12 year-old. This choice of dummies reflects the fact that small females are more likely than males to suffer serious head injuries in real-world side impacts (see Attachment 2, Table 3). The head of the smaller SID-IIs driver dummy is in the window area where people's heads are more vulnerable to being struck by the front end of a striking vehicle in a real-world side impact.
How vehicles are evaluated in the Institute's side impact tests
Each vehicle's overall side impact evaluation is based on (1) the injury measures recorded on the two instrumented SID-IIs dummies, (2) an assessment of head protection countermeasures, and (3) the vehicle's structural performance during the impact.
(1) Injury measures are obtained from two SID-IIs dummies, one in the driver seat and the other in the rear seat behind the driver. These measures are used to determine the likelihood that a driver and/or passenger would have sustained serious injury to various body regions. Measures are recorded from the head, neck, chest, abdomen, pelvis, and leg. These injury measures, especially from the head/neck and torso (chest and abdomen), are major components of each vehicle's overall evaluation.
(2) To supplement head injury measures, the movements and contacts of the dummies' heads during the crash are evaluated. This assessment is more important for seating positions without head protection airbags, which (assuming they perform as intended) should prevent injurious head contacts. Very high head injury measures typically are recorded when the moving deformable barrier hits a dummy's head during impact. However, a "near miss" or a grazing contact also indicates a potential risk of serious injury in a real-world crash. This is because small differences in occupants' heights or in their seating positions compared with the test dummies could result in a hard contact and high risk of serious head injury. In the rear seat, the potential for serious injury is influenced by whether the seating position puts occupants' heads in proximity to areas designed with padding or something else to reduce impact forces versus areas with hard or unprotected structures. Analysis of the movement and contact points of the dummies' heads during the side impact crash test is used to assess this aspect of protection.
(3) Structural performance is based on measurements indicating the amount of intrusion into the occupant compartment around the B-pillar (between the doors). This assessment indicates how well a vehicle's side structure resisted intrusion into the driver and rear-seat passenger space. Some intrusion into the occupant compartment is inevitable in serious side impacts. Any intrusion that does occur should be uniform both horizontally and vertically and shouldn't seriously compromise the driver and passenger space.
The three factors evaluated in the Institute's side impact test — driver and passenger injury measures, head protection, and structural performance — determine each vehicle's overall side crashworthiness evaluation. The order in which vehicles are listed (see Attachment 1) depends on performance in frontal offset crash tests as well as side impact tests.