Automobile Crash Tests

There are two major organizations which crash test automobiles and report the results to the public. One is the National Highway Traffic Safety Administration, (NHTSA), an agency of the United States government. The other is the Insurance Institute for Highway Safety, (IIHS), a non-profit organization funded by auto insurers.
Both work to reduce the number of motor vehicle crashes, and the rate of injuries and amount of property damage in the crashes that still occur. They each conduct basic research and produce ratings for each model of vehicle.
The Insurance Institute’s frontal crash testing differs from that of the NHTSA New Car Assessment Program in that its tests are offset from the center. This test exposes 40% of the front of the vehicle to an impact with a deformable barrier at approximately 40 mph (60 km/h). Because only 40% of the vehicle’s front must withstand the impact, some contend it shows the structural strength better than the NHTSA New Car Assessment Program full-width testing does. 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.
NHTSA uses a star rating to rate cars for performance in frontal impacts, side impacts and rollovers. A five star rating is the highest.
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. The IIHS recently introduced a side impact test which differs from that of NHTSA. NHTSA tests with a low barrier. The IIHS uses an elevated barrier to simulate the impact of an SUV (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 many new vehicles achieve 4-5 stars from the NHTSA, many do not score well in the IIHS side impact test. The IIHS also evaluates vehicles’ bumpers in a series of 5 mph (8 km/h) impacts, as well as seat and head restraint designs in relation to rear-impact protection, using the same Poor-Good rating system.
The IIHS and NHTSA tests can differ. For example, in a series of tests, NHTSA graded the Chevrolet Venture (also marketed as Oldsmobile Silhouette, Pontiac Montana/TransSport) as 4/5 stars, but the IIHS graded it “Poor” due to its poor structural integrity which becomes apparent in the offset crash test.