The Insurance Institute for Highway Safety has launched a new crash test program to see if a vehicle's design protects the front seat passenger as well as the driver. Vehicle models must pass this test in order to qualify for the IIHS Top Safety Pick+ award for 2018.

IIHS developed the test after its researchers conducted a study last year which found that vehicles with good driver protection may neglect similar safeguards for the front seat passenger. The study conducted a "small overlap" test on seven small SUVs with model years between 2014 and 2016, simulating crashes involving 25 percent of the vehicle's width. This kind of test simulates crashes where a front corner of a vehicle collides with a vehicle, utility pole, or other object.

In the 2016 study, all seven SUV models earned good ratings for driver side protection on the IIHS scale of good, acceptable, marginal, or poor. However, only one model also received a good rating for passenger side protection; three were deemed acceptable, two marginal, and one poor.

The small overlap test on the driver's side was first introduced by IIHS in 2012, and became part of its awards criteria a year later. Most vehicles earned poor or marginal ratings at first, since the small overlap test bypasses most of the vehicle's primary structure and is more difficult to pass than a head-on crash test. Automakers have since taken steps such as strengthening the occupant compartment or extending the bumper to offer more protection in small overlap crashes, and two-thirds of 2017 models earned a good rating in the test.

IIHS says it initially focused only on the driver's side since every vehicle on the road has a driver but not all of them have a passenger. It notes how automakers cannot always mirror driver's side protection for the passenger side, since vehicles are asymmetrical to a certain degree. The new test requires a vehicle to receive a good or acceptable rating in a passenger side small overlap test in order to receive the highest award from the institute.

The new crash test is essentially the same as the existing small overlap test, except it takes place on the right side and includes crash test dummies for both the driver's seat and front passenger seat. A vehicle is propelled at a barrier at 40 miles per hour, with the impact affecting 25 percent of the vehicle's width on the passenger side.

IIHS used the passenger side small overlap test on 13 midsize cars with 2017-2018 model years. These vehicles performed significantly better than the SUVs in last year's test, with 10 earning good ratings. One was rated acceptable, while two received marginal ratings.

"The midsize cars we tested didn't have any glaring structural deficiencies on the right side," said Becky Mueller, senior research engineer at IIHS. "Optimizing airbags and safety belts to provide better head protection for front seat passengers appears to be the most urgent task now."

All 13 vehicles received good or acceptable ratings on structure, and all but one earned good or acceptable ratings on all four passenger injury measures. However, three models—the Chevrolet Malibu, Volkswagen Passat, and Volkswagen Jetta—received marginal ratings for passenger restraints and kinematics. The Malibu and Passat had marginal ratings overall, while the Jetta was rated acceptable overall.

In the Malibu and Passat tests, the head of the crash test dummy in the passenger's side slid off the front airbag and hit the dashboard. IIHS says measurements taken from the dummy showed that a passenger could have suffered head injuries if the same result occurred in a real world crash.

Some vehicles showed significantly more structural intrusion into the occupant compartment on the passenger's side. The Passat had a maximum intrusion of seven inches at the lower door hinge pillar, compared to four inches on the driver's side. The Mazda 6 had the greatest intrusion on the passenger side at nine inches, which was four inches greater than on the driver's side; however, the vehicle still earned a good rating due to the sufficient performance of its airbags.

IIHS says it will also have a test verification process to allow more vehicles to qualify for the Top Safety Pick+ award than the institute would normally be able to test. In this process, the automaker can provide data from its own tests, conducted using IIHS protocol. IIHS can then assign a rating based on this information and occasional audits.