DETROIT — A new method of crash-testing minivans showed that Honda, Nissan and Toyota models are among the safest when struck by a sport utility vehicle or a pickup truck, according to a report released Sunday.

The Insurance Institute for Highway Safety assessed the safety of six minivans by simulating a crash in which an SUV or a pickup truck slammed into the side of the minivan at 31 mph. The tests involved only new models that were not going to be redesigned by the manufacturer in the near future.

The insurance institute found that drivers' heads were most protected in minivans with side air bags that cushioned the head as the minivan was hit. New Toyota Siennas, Nissan Quests and Honda Odysseys, all with standard head-curtain air bags, were the top performers in the study.

The Ford Freestar and Mazda MPV, which have curtain air bags as optional equipment, fared worst in the study.

The institute's new method of testing uses a barrier that simulates a side-impact crash with a vehicle larger and higher than the typical passenger car. Current federal-agency tests simulate a collision only between a car and a minivan.

"If you look at the current passenger vehicle fleet out there, SUVs and pickups are a significant portion," said Brian O'Neil, the insurance institute's president. "When the federal government developed their test, that was in the 1980s and the vehicle fleet has changed tremendously since then."

The National Highway Traffic Safety Administration, a federal Transportation Department agency, is expected to overhaul its tests significantly early next year.