Rear-seat passengers are not well protected by small pickups’ safety systems, new moderate overlap front crash tests by the Insurance Institute for Highway Safety found.

The IIHS rated the Nissan Frontier acceptable. The Ford Ranger earned a marginal rating — higher than poor but lower than acceptable — while the Chevrolet Colorado, Jeep Gladiator and Toyota Tacoma all received poor ratings. The ratings only apply to the crew cab versions.

The test propelled vehicles down a 600-foot runway and crashed them into a barrier at 40 mph with 40 percent impact to the front of the vehicle. Driver and rear-seat passenger dummies and cameras in the vehicles helped measure the success of the vehicles’ safety systems.

The IIHS rates the vehicles on how well the vehicle’s structure held up, injury measures recorded by two dummies inside the vehicles and how well the restraints controlled the movement of those dummies.

All five vehicles provided good protection for the dummy in the front seat, the tests found, but the rear-seat dummies did not fare as well.

The rear-seat dummy slipped under the seat belt in the Ranger. Shifting of the seat belt from its proper position increases the risk of internal injuries.

In the Ranger, Tacoma, Frontier and Colorado, the rear dummy’s head came close to the front seat back.

The Gladiator lacks side curtain airbags, which the IIHS said increases the risk of injury from a hard impact.
 

The rear-seat dummies in the Colorado, Gladiator and Tacoma recorded a moderate or likely risk of both neck and chest injuries. The dummy in the Ranger recorded moderate risk of chest injuries.

The IIHS has previously tested five popular cars and 28 crossovers and SUVs using the updated test.

Only six — the Ford Explorer, Ford Mustang Mach-E, Subaru Ascent, Tesla Model Y, Ford Escape and Volvo XC40 — have earned good ratings, the highest.