Question: What vehicle received the first ‘double best pick’ designation from the Insurance Institute for Highway Safety (IIHS)?

Answer: The 2005 Saab 9-3.  The car is the first ever to receive ‘best pick’ designation in both frontal and side crash tests.

IIHS's frontal-offset crash test at 40 mph. NHTSA's frontal crash test at 35 mph. NHTSA's side crash test at 38.5 mph.

The National Highway Traffic Safety Administration (NHTSA) as well as the IIHS, the two major purveyors of crash test results, perform different types of crash tests at different speeds. They test different safety components for each vehicle. Neither test is better, but for a car buyer, looking at the overall combination of crash test results can steer you toward the safest car you can afford.

However, some critics charge that the federal government should do more extensive and rigorous testing of new vehicles. NHTSA's existing crash tests are "full of shortcomings from A to Z," says Gerald Donaldson of Advocates for Highway and Auto Safety, a nonprofit group that lobbies for safety regulations at the state and federal levels. Donaldson says NHTSA should implement more rigorous testing procedures for new vehicles.

Donaldson points to the crash test results in 2001 of the Ford F-150 pickup which received both a five-star rating, the highest rating available, in government crash tests performed by the National Highway Traffic Safety Administration (NHTSA) and a grade of  "poor" overall in testing by the Insurance Institute for Highway Safety (IIHS).  "Those discrepancies in results are very telling," says Donaldson. "It makes a difference to me, and to what I would buy if I saw that kind of discrepancy."

In June of 2003, IIHS began conducting side-impact crash tests for the first time.  The configuration of Institute’s side impact crash 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 mimic the typical front end of a pick-up or SUV.  In each side-struck vehicle are two instrumented dummies, one in the driver’s seat and the other in the rear seat behind the driver.  These dummies are the size of a short female or a 12 year-old child. 

Different tests can mean conflicting results

It's the law that all new cars sold in the U.S. maintain minimum levels of crash protection at 30 mph.

Crash test ratings explained The National Highway Traffic Safety Administration rates vehicles on a scale of one to five stars: Frontal crash ratings: means a 46 percent or greater chance of serious injury in a crash. means a 36 percent to 45 percent chance of serious injury. means a 21 percent to 35 percent chance of serious injury. means an 11 percent to 20 percent chance of serious injury. means a 10 percent or lower chance of serious injury. Side crash ratings: means a 25 percent or greater chance of serious injury. means a 21 percent to 25 percent chance of serious injury. means an 11 percent to 20 percent chance of serious injury. means a 6 percent to 10 percent chance of serious injury. means a 5 percent or lower chance of serious injury. The Insurance Institute for Highway Safety rates vehicle safety on the following scale: Good Acceptable Marginal Poor

Auto makers conduct their own tests to ensure their vehicles comply. Then NHTSA, a division of the U.S. Department of Transportation, crashes new cars into a full-width fixed barrier at 35 mph, simulating a head-on frontal crash into a fixed object such as a wall or bridge abutment.

NHTSA also performs side-impact crash tests that mimic a "t-bone" accident, such as often happens at intersections, by crashing a 3,015-pound barrier into the side of a stationary vehicle at 38.5 mph. NHTSA also calculates rollover resistance ratings, meaning the likelihood that a vehicle will roll over on the road, by using mathematical equations, not by actually tipping the vehicles over.

Each vehicle tested by NHTSA receives between one and five stars for crash test performance (see sidebar at left). The stars can only be compared among vehicles in the same weight class — so, for example, you can't compare a five-star Volkswagen Jetta with the three-star Toyota 4Runner SUV.

NHTSA's frontal crashes allow the car's entire front end to absorb the crash impact. This allows the safety cage to remain intact in most cases. But because the barrier is immobile, the car's deceleration is very fast — an effective measure of the restraint systems, including air bags and safety belts.

IIHS, funded by a group of 74 insurers, crashes 40 percent of a car's front end into a barrier at 40 mph, in what's termed a frontal-offset crash test. That differs two ways from NHTSA's test: It's not head-on and it's at a higher speed. But IIHS's barrier is also not fixed; it is deformable, mimicking a crash between two vehicles rather than a crash where one strikes a fixed object.

IIHS rates crash-tested vehicles on a four-step scale: Good (the best rating), acceptable, marginal, and poor. Vehicles receive ratings for the following:

• Overall performance.
• Structure and safety cage.
• The likelihood of serious injury in a crash. The effectiveness of air bags, seat belts, and head restraints in controlling the crash test dummy during the crash.

IIHS also conducts a series of low-speed crash tests at 5 mph that assess bumper-damage repair costs if a vehicle is driven into a pole or other fixed object.

Debate over crash test usefulness

Because frontal-offset crashes put stress on a smaller area of the car's structure, they are more useful for testing the likelihood that the side of the car hit in a crash will crumple and intrude upon the occupants' space. Here is where the F-150 doesn't live up to its five-star NHTSA rating: Pictures of the crashed F-150, provided by IIHS, show the truck's front end completely crumpled, with the passenger compartment destroyed. The collapse "left little survival space for the driver," says the IIHS. Both driver-side doors partially opened during the crash, and the driver's seat pitched forward, wedging the dummy into a narrow space made smaller by the collapse of the compartment.

"In NHTSA's test, because the barrier is rigid, the deceleration in the test is faster, so it's a better and more demanding test of the restraint system," says Anne Fleming of the IIHS. "Our tests are harder on the structure. What you get out of the two tests is a fuller view of the vehicle's overall safety."

"It's engineering. The base elements are the same; everybody uses steel," says Dan Johnston of Volvo. "It's how you engineer that steel that affects how it performs. What you want, ideally, is the ability to absorb energy and create an environment where there's a high degree of survivability."

"Concentrating the impact on a portion of the car has dramatic effects on the crashworthiness of a vehicle," says Donaldson of Advocates for Highway and Auto Safety. "Lots of cars, such as the F-150, are passing with flying colors from NHTSA, but the [IIHS] offset tests shows that there's commonly tremendous intrusion in the footwell area," even if the car's safety cage remains intact, he says. That footwell intrusion can mean serious leg and lower-body injuries.

Continue to Page 2: Automaker crash tests: A "big" secret for some