Both SUVs showed a high likelihood of injuries in a passenger-side small-overlap crash.
The IIHS began testing both the driver and passenger sides after noticing that some automakers appeared to be reinforcing vehicle structures only for the driver-side impact.
Apparently lacking symmetrical reinforcement, the Explorer showed maximum intrusion of 15 inches into the cabin at the lower door hinge pillar. Dummy measurements point to a high likelihood of injuries to the right hip and the possibility of injuries to the left lower leg.
"The Explorer also had poor structural performance in the driver-side test and earns an overall rating of marginal for driver-side small overlap protection," the IIHS notes. " Ford is redesigning the Explorer and says the new model will have improved small overlap protection on both sides."
The Grand Cherokee experienced maximum intrusion of 10 inches at the lower door hinge pillar.
"More alarming was what happened to the passenger dummy's head," the report notes. "It hit the dashboard hard through the front airbag and then, because the side curtain airbag didn't deploy and the door opened, it moved outside the vehicle during rebound."