"The reason there are six instead of three is that we've got two different orientations for the car that you're backing toward," said Zuby.
The seventh scenario involves backing into a parking space toward the side one of the adjacent cars as if the vehicle is misaligned, said Zuby, and the eighth scenario involves backing into a pole. Each scenario includes three trial runs.
To nab a superior rating, a vehicle must have a rear auto-brake system that can prevent a crash at 4 mph or barely hit the target and reduce speed to 1 mph. Under the six point system, vehicle models must gain 4.5 points or more to earn a superior rating, and more than half a point to earn an advanced rating.
To highlight repair costs associated with rear crashes, the nonprofit organization carried out 4 tests with and without the auto-brake. Some of the scenarios included an XT5 reversing into a pole and an Outback backing into a 2016 Chevrolet Cruze. The vehicles did not hit anything with the auto-brake.
The damages to the XT5 after backing into the pole amounted to $3,477 in repairs, and when the Outback reversed into the Cruze's rear bumper, damages amounted to $1,159 for the Outback and $740 for the Cruze.
New research from IIHS indicates that utilizing the rear-view mirror, parking sensors and rear auto-brake in unison minimizes rear crashes reported to the police by 78 percent, IIHS said in a statement.
"We do plan to expand the ratings to cover more makes and models," said Zuby. "But for the initial set of ratings we're just showing among these six."