Several mid-size cars have made strides in protecting motorists in side crashes through standard air bags and improved designs, the insurance industry reports.

Crash test results released Thursday by the U.S. Insurance Institute for Highway Safety gave top scores in front-end and side-impact crashes to the 2008 Chevrolet Malibu, Saturn Aura, Dodge Avenger, Nissan Altima, Infiniti G35 and Mitsubishi Galant. The 2008 Kia Optima received the highest score in front-end tests and the second-highest score in the side test.

David Zuby, the Institute's senior vice-president, said 10 similar vehicles tested in 2004 without side air bags received the lowest rating of "poor" in the side tests. Only past generations of the Honda Accord, Toyota Camry and Chevrolet Malibu received the top score in 2004 when they were tested with side air bags.

"The side impact results represent a huge change from just four years ago," Zuby said.

Optima earns top scores in rear-crash tests

In rear-end testing, the results were mixed. The Optima was the only vehicle tested to receive a top rating, followed by the Avenger, which received the second-highest score of "acceptable."

Four of the vehicles — G35, Altima, Malibu and Aura — received the second-lowest score of "marginal" and the Galant received the lowest rating of "poor." Rear crashes can lead to neck injuries, which rack up two million insurance claims a year costing at least $8.5 billion US.

Dan Irvin, a Mitsubishi spokesman, said the Galant meets all federal safety standards and the automaker "continuously strives to improve the safety performance of our vehicles."

Carolyn Markey, a General Motors Corp. spokeswoman, said the rear tests were one measure of crash performance and their vehicles' head restraints were designed "to accommodate a variety of drivers."

Kia spokesman Alex Fedorak said the automaker had a "strong safety record" and noted the IIHS has said its side-impact test features severe crash conditions.

Max Gates, a Chrysler spokesman, said the automaker's priority "continues to be designing vehicles that perform safely for our customers and their families in 'everyday' driving conditions."

Zuby said side air bags were largely optional equipment when the institute conducted the tests in 2004. But side air bags are standard in all seven of the 2008 vehicles the institute reviewed.

The institute's frontal crash test simulates a 64 km/h crash and its effect on the driver, while the rear test simulates a 32 km/h test. The side crash simulates what would happen if the vehicle was struck in the side by a sport utility vehicle at 49 km/h. The side crash test uses dummies in both the front and rear seats.