The U.S.-based IIHS developed the updated side crash test after research showed that many of the real-world side impacts that still account for nearly a quarter of passenger vehicle occupant fatalities are more severe than the original evaluation.

The tougher side crash test uses a heavier barrier traveling at a higher speed to simulate the striking vehicle. The new barrier weighs 4,200 pounds (1,905 kilograms)—close to the weight of today’s midsize SUVs—and strikes the test vehicle at 37 mph (60 km/h), compared with a 3,300-pound barrier (1,496 kilograms) traveling at 31 mph (50 km/h) in the original evaluation.

When subjected to this new side-impact crash test, the Subaru XV (U.S. market Crosstrek) and Impreza showed more substantial intrusion of the B-pillar and interior door panels, and into the occupant compartment. It also happened to encroach on the survival space and contributed to a relatively high risk of torso injuries for the driver and rear passenger. In addition, the head of the driver dummy also moved downward past the side curtain airbag to hit the windowsill, indicating inadequate head protection.

This means that the Subaru XV and Impreza both receive a “Poor” rating along with the Kia Forte. Three other compacts—the Nissan Sentra, Toyota Corolla, and Honda Civic—receive an “Acceptable” rating. Only the Mazda3 managed a “Good” rating.

All of these vehicles earned “Good” ratings in their original side impact test.

For now, the updated test is not included in the IIHS award criteria. However, starting in 2023, a Good or Acceptable rating will be required for the lower-tier Top Safety Pick award and a good rating will be needed for the higher-tier Top Safety Pick+.