DETROIT -- The Audi A4 and Chevrolet Malibu won top scores in side impact crash tests conducted recently by a U.S. vehicle safety group with links to the insurance industry.

The Insurance Institute for Highway Safety said three other 2005 model mid-size cars failed to win its "good" or "best pick" designation in the recent tests, however. They include Nissan Motor Co. Ltd.'s Maxima and the Volvo S60, from a company known as a perennial safety leader.

In the rigorous tests, cars are struck in the driver's side with a 3,300-pound barrier meant to simulate a typical pickup truck or SUV.

The Malibu, equipped with optional side airbags, and the Audi A4 with standard side airbags both got "good" or "best pick" ratings in the tests.

The A4 also joined company with the Saab 9-3 as the only other car to win top scores in both the side impact test and an earlier frontal offset crash test conducted by the Insurance Institute.

The performance of the Volvo S60, with standard head and torso airbags, was not as good as the A4's or Malibu's, though. The Insurance Institute said it only warranted its second-highest rating of "acceptable."

"Even though the S60 has standard torso airbags for front-seat occupants along with the curtains, a fractured pelvis for the driver would be likely in a real-world crash like this," said Adrian Lund, the Institute's chief operating officer, in a statement.

"Volvo still has some work to do to improve the S60's performance," he said.

In earlier tests conducted by the Institute, Volvo's S40 sedan also failed to win a "good" rating. Volvo is part of Ford Motor Co.'s stable of European luxury brands.

The Nissan Maxima and relatively inexpensive Suzuki Verona, from Suzuki Motor Corp., both got "marginal" ratings in the Institute's latest tests, meanwhile, just one notch above its lowest rating of "poor."

"The results for the Verona and Maxima show that vehicles with weak side structures are unlikely to provide effective protection in serious side crashes, even if they're equipped with head-protecting airbags," the Institute said.