Of four popular minivan models tested in the Insurance Institute for Highway Safety (IIHS) updated moderate overlap front crash test, not one earned an acceptable or good rating.

The Chrysler Pacifica, Kia Carnival and Toyota Sienna are rated marginal, while the Honda Odyssey is rated poor.

All four minivans provide good protection in the front seat. But each is plagued by multiple issues when it comes to the second row.

“The restraint systems in all four vehicles leave the second-row occupant vulnerable to chest injuries, either because of excessive belt forces or poor belt positioning,” said Jessica Jermakian, IIHS vice president of vehicle research. “That’s concerning because those injuries can be life-threatening.”

Of the four vehicles, only the marginal-rated Sienna is equipped with belt pretensioners and force limiters, technologies designed to reduce belt forces, the IIHS said. The rear dummy submarined beneath the lap belt, and the shoulder belt migrated off the shoulder toward the dummy’s neck during the test.

In the two other marginal vehicles, the Carnival and Pacifica, the seatbelt exerted too much force on the dummy’s chest. The side curtain airbag of the Pacifica also did not deploy during the test.

The forces on the rear dummy’s neck were within reasonable limits in the Pacifica and Sienna but substantially higher in the Carnival, increasing the chances of a head or neck injury.

The poor-rated Odyssey test revealed the forces on the head and neck were even higher, and the crash video demonstrated that the rear seatbelt allowed the dummy’s head to come too close to the front seatback, increasing the risk of head injuries.

All but the Sienna also lack seatbelt reminders for the second-row seats.

The test, which now emphasizes back seat safety, after research revealed the risk of a fatal injury in newer cars is now higher for belted occupants in the second row than for those in front.

This is the result of safety improvements for front seat occupants, like improved airbags and advanced seatbelts rarely available for occupants located in back.

The back seat still remains the safest place for children, who can be injured by an inflating front airbag, and the rating does not apply to children secured properly in child safety seats.

According to the safety researcher, in the updated test, a second dummy is positioned in the second row behind the driver. The driver dummy is the size of an average adult man. The rear dummy is the size of a small woman or 12-year-old child.

IIHS researchers developed new metrics that focus on the injuries most frequently seen in back seat passengers.

For a vehicle to earn a good rating, there can’t be an excessive risk of injury to the head, neck, chest or thigh, as recorded by the second-row dummy. The dummy must remain correctly positioned during the crash without “submarining,” or sliding forward beneath the lap belt, increasing the risk of abdominal injuries.

The head should also remain a safe distance from the front seatback and the rest of the vehicle interior, and the shoulder belt should remain on the shoulder, where it is most effective, the IIHS stated.

A pressure sensor located on the rear dummy’s torso is used to check the shoulder belt position during the crash.

As in the original test, the structure of the occupant compartment must maintain adequate survival space for the driver, and measurements taken from the driver dummy shouldn’t show an excessive risk of injuries, the IIHS added.

“Back seat safety is important for all vehicles, but it’s especially vital for those, like minivans, that customers are choosing specifically to transport their families,” said IIHS President David Harkey. “It’s disappointing that automakers haven’t acted faster to apply the best available technology to the second row in this vehicle class.”