Seven of eleven small cars tested earned good or acceptable ratings in the IIHS' new, tougher side-impact test, but four models are rated poor

Insurance Institute for Highway Safety 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 Mazda 3 sedan and Mazda 3 hatchback earn good ratings. Five other vehicles - the Nissan Sentra, Toyota Corolla sedan, Toyota Corolla hatchback, Honda Civic sedan and Honda Civic hatchback - are rated acceptable. The Kia Forte, Subaru Crosstrek and the Subaru Impreza sedan and wagon are rated poor.

All 11 vehicles earn good ratings in the original side test.

The updated 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 kg) - close to the weight of today's midsize SUVs - and strikes the test vehicle at 37 mph (59,5 km/h), compared with a 3,300-pound (1,497 kg) barrier traveling at 31 mph (49,9 km/h) in the original evaluation.

In earlier IIHS tests of small SUVs, midsize SUVs and midsize cars, a higher ride height seemed to translate into better performance in the new evaluation. A taller vehicle means the moving barrier strikes nearer to the floor of the occupant compartment. The results from the small cars suggest that vehicle length - in particular, the length of the occupant compartment- may also play a role.

"Doors tend to be weaker than the B-pillar and the frame surrounding the occupant compartment. Small cars have less of that weaker space because of their shorter wheelbase and occupant compartment," said Raul Arbelaez, vice president of the Institute's Vehicle Research Center.

The poor-rated Forte, for example, had driver measurements that indicated a high risk of injuries to the torso and pelvis area, as well as a head or neck injury. The driver dummy's head made hard impact with the windowsill through the side curtain airbag, and the structure of the occupant compartment was not maintained well, contributing to a moderate risk of injuries to the rear passenger's torso and pelvis.

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+.

Source: IIHS