Insurance Institute for Highway Safety (IIHS)

The Insurance Institute for Highway Safety is a U.S. non-profit organization funded by auto insurers. It works to reduce the number of motor vehicle crashes, and the rate of injuries and amount of property damage in the crashes that still occur. It carries out basic research and produces ratings for each model of vehicle.

The Institute’s crash testing differs from NHTSA’s New Car Assessment Program (governmental) in that the Insurance Institute for Highway Safety tests are ‘offset’ from the center. These ‘offset’ tests expose 40% of the front of the vehicle to an impact with a deformable barrier at approximately 40 mph. Because only 40% of the vehicle’s front must stand the impact, it shows the structural strength much better than the U.S. Government’s NHTSA New Car Assessment Program full-width testing. Many real-life frontal impacts are offset.

The IIHS uses four ratings for each category, Good (best, green G), Acceptable (yellow A), Marginal (orange M) and Poor (worst, red P). Vehicles which score Good in all the various rating categories, or which have only one Acceptable category, are given Best Pick designations.

As with NHTSA’s New Car Assessment Program testings, vehicles across different categories may not be directly compared, as increased weight is beneficial in a two-vehicle crash.

Relatively new to the IIHS is the side impact test. Unlike NHTSA New Car Assessment Program test’s low barrier, the IIHS uses an elevated barrier to simulate the impact of an sport utility vehicle (approximately half of all new cars sold) into the side of the vehicle being tested. This is a “very demanding” test of both the structural integrity of the vehicle, as well as the restraints. While most new vehicles achieve 4 and 5 stars from the NHTSA (where head injuries are not part of the rating), many do not score well in the IIHS side impact test. Side impact airbags greatly help vehicles score higher in the test. The IIHS side impact test more accurately reflects a real side impact involving an SUV as the vehicle that impacts into the side of another.

The IIHS also evaluates vehicles’ bumpers in a series of 5-mph impacts, as well as seat and head restraint designs in relation to rear-impact protection, using the same Poor-Good rating system.

When purchasing a new vehicle, it is necessary to pay attention to both the IIHS and NHTSA test. For example, a Chevrolet Venture (also marketed as Oldsmobile Silhouette, Pontiac Montana/TransSport) achieves a respectable rating of 4/5 stars from NHTSA, but is rated Poor by the IIHS for its poor structural integrity which becomes apparent in the offset crash test.

NHTSA test of the Chevy Venture.

Insurance Institute for Highway Safety test of Chevy Venture (1997 Pontiac Trans Sport tested).

Insurance Institute for Highway Safety test of Chevy Venture (post-crash, 1997 Pontiac Trans Sport tested).

The difference of results between the same model tested by the NHTSA and IIHS are great and must be considered when deciding the safety of a vehicle.