The test, known as a small overlap crash, propels a car at 40 mph into a five foot high stationary object, hitting only the corner of the car into the object. Since the crash bypasses most of the car's ability to absorb the crash, vehicles fared much worse in the small overlap crash, intended to simulate hitting a pole, tree or the edge of another vehicle.
"Nearly every new car performs well in other frontal crash tests conducted by the Institute and the federal government, but we still see more than 10,000 deaths in frontal crashes each year," Institute president Adrian Lund said. "This new test program is based on years of analyzing real-world frontal crashes and then replicating them in our crash test facility to determine how people are being seriously injured and how cars can be designed to protect them better. We think this is the next step in improving frontal crash protection."
While cars makers have created much more robust crash cages around the passenger compartment of most vehicles, there appears to be a weakness on the edges of that cage, especially if only the edge hits an object.
In one instance, the Volkswagen CC sheared off its door during the accident. Furthermore, IIHS found that there appears to be a gap in airbag coverage during these accidents, allowing drivers to sometimes hit their heads against the bar that holds up the windshield, known as the A pillar.
The gap in airbag coverage occurs when the side airbags do not deploy and the front airbag on the steering wheel shifts to the middle of the car during impact. During testing of the MKZ, the driver's head missed all of the airbags during the accident test.Many of the side curtain airbags do not push far enough forward to protect someone from the A pillar, researchers noted.
"These are severe crashes, and our new test reflects that," Lund said. "Most automakers design their vehicles to ace our moderate overlap frontal test and NHTSA's full-width frontal test, but the problem of small overlap crashes hasn't been addressed. We hope our new rating program will change that."
The influential automotive magazine "Consumer Reports" applauded the new IIHS test but noted some potential problems as well.
"As manufacturers design to do well in this test, it might mean adding weight, which in turn would adversely affect fuel economy," it said. "Such trade-offs have always been the price to pay in safety engineering. But if it's a real life-saver, we believe a trivial sacrifice in fuel economy is well worth it."
The three 2012 cars that successfully passed the test included the Volvo S60, the Acura TL and the Infiniti G with an acceptable rating.
The other eight that failed the test include: The BMW 3 Series, the Acura TSX, the Lincoln MKZ, and the Volkswagen CC all scored marginal ratings. The Mercedes C-Class, the Lexus IS 250/350, the Audi A4, and Lexus ES 350 all earned poor ratings.
The IIHS focused on luxury cars because those typically have the strongest safety ratings out of any vehicles and are the first to adopt new safety features.