Understanding IIHS Ratings Car shoppers will benefit from having NHTSA stars available at the dealer, but they should also be aware of IIHS ratings, which are based on slightly different methodologies.

There are two primary organizations that conduct crash tests and rank vehicles accordingly. NHTSA will provide the star ratings soon to be prominently displayed on window stickers, and the other, the Insurance Institute for Highway Safety (IIHS), is a non-profit group that is supported by insurance companies. The IIHS ranks each vehicle from Poor to Good, with exceptional vehicles labeled a Best Pick. Car shoppers will benefit from having NHTSA stars available at the dealer, but they should also be aware of IIHS ratings, which are based on slightly different methodologies.

Instead of NHTSA’s full frontal test, IIHS performs offset frontal crashes. After being fitted with crash dummies, the test vehicle reaches 40 mph and strikes a deformable barrier. However, only the front driver’s side takes the hit, so all of the crash energy must be absorbed by a smaller area of the vehicle’s structure – the result is a tougher test.

Side impact tests are conducted at 31 mph, with a perpendicular impact from a 3,300-lb. deformable barrier that is designed to mimic a larger and taller vehicle, such as a pickup truck or SUV. Given the number of such vehicles on the road today, IIHS believes that this bigger barrier best represents real-world accident scenarios.

Rear crashes are conducted to evaluate seat and headrest design and the likelihood of whiplash injuries. These tests mirror the effect of being hit from behind at 20 mph by a vehicle of equal weight. And finally, this being an insurance company-based group, four low-speed impact tests, replicating what happens to drivers in congested traffic every day, are conducted to determine front and rear bumper efficacy and repair costs.