DETROIT » Only two of nine midsize SUVs got the highest rating in crash tests done by an insurance industry group.

The Chevrolet Equinox and GMC Terrain, both made by General Motors, received the highest "good" rating from the Insurance Institute for Highway Safety. The Toyota Highlander got the second-best "acceptable" rating in tests of 2014 models.

But the Jeep Grand Cherokee, Toyota 4Runner and Ford Explorer got "marginal" ratings, while the Kia Sorento, Mazda CX-9 and Honda Pilot all were rated "poor."

The ratings are based on six crash test measurements done by the institute. Only the Equinox and Terrain got "good" ratings in a front overlap crash that mimics what happens when a car’s front corner collides with another vehicle or an object like a utility pole. In the test, 25 percent of a vehicle’s front end on the driver’s side strikes a rigid barrier at 40 mph.

The test, instituted in 2012, is more difficult than the U.S. government’s frontal crash test, in which a car strikes a rigid barrier head-on at 35 mph. IIHS says hitting only part of the front end makes it harder for cars to manage the energy from a crash. The test "continues to challenge manufacturers more than a year and a half after its introduction," the institute said in a statement.

The institute uses its crash test scores to prod automakers into adding safety devices or making their cars more crash-resistant.

The institute said the Equinox and Terrain, which are almost identical, were modified by GM in the new model year to strengthen their front structure and door-hinge pillars. In tests, the Equinox driver’s space was well-maintained, and the crash dummy’s movement was well-controlled, the institute said.

The institute changed its requirements for vehicles to get the "Top Safety Pick-Plus" designation this year. To earn that, vehicles must get "good" ratings in four crash tests, "good" or "acceptable" in the overlap test, and they must have available a front crash prevention system that either warns the driver of a crash or stops the vehicle with automatic braking.

Of the nine midsize SUVs, only the Equinox and Terrain and the Highlander qualified for "Top Safety Pick-Plus."

The Honda Pilot was the worst performer of the group, largely because the driver’s space was seriously compromised in the overlap test, the institute said.

Honda said in a statement that with each redesign, the Pilot has been a leader in light-truck safety and driver-assist technologies "and we are committed that it will continue to do so in the future."