Insurance Institute for Highway Safety
The Insurance Institute for Highway Safety (IIHS) is a U.S. non-profit organization funded by auto insurers, established in 1959 and headquartered in Arlington, Virginia. 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 research and produces ratings for popular passenger vehicles as well as for certain consumer products such as child car booster seats.
Frontal crash tests
Moderate overlap frontal test
The Institute's front crash test differs from that of the American government's National Highway Traffic Safety Administration (NHTSA) New Car Assessment Program in that its tests are offset. This test exposes 40% of the front of the vehicle to an impact with a deformable barrier at approximately 40 mph (64 kph). Because only 40% of the vehicle's front must stand the impact, it shows the structural strength better than the NHTSA's full-width testing does. The IIHS began this crash test in January 1995.
Many real-life frontal impacts are offset. However, the NHTSA's full frontal crash tests result in the occupant compartment going through greater deceleration. The full frontal crash test is more suitable for evaluating restraint systems such as seat belts and airbags.
The IIHS and NHTSA test results can differ; for example, the NHTSA gave the Chevrolet Venture (also marketed as the Oldsmobile Silhouette and Pontiac Montana/TransSport) 4/5 stars (with 5 stars being the best and 1 star the worst), but the IIHS rated it "Poor" for its poor structural integrity which becomes apparent in the offset crash test. This minivan was one of the poorest performers since the offset frontal crash tests were begun in 1995. The same applies for the 1997–2003 Ford F-150.
IIHS test of Pontiac Trans Sport
An analysis by the IIHS found that a driver of a vehicle rated "Good" is 46% less likely to die in a frontal crash, compared with a driver in a "Poor" rated vehicle . A 33% reduction was found for driver's in an "Acceptable" or "Marginal" rated vehicle.
The IIHS evaluates six individual categories, assigning each a "Good", "Acceptable", "Marginal", or "Poor" rating before determining the vehicle's overall frontal impact rating. 
- It is important to note, as with the NHTSA's frontal impact test, vehicles across different weight categories may not be directly compared. This is because the heavier vehicle is generally considered to have an advantage if it encounters a lighter vehicle or is involved in a single-vehicle crash. The IIHS demonstrated this by crashing three midsize sedans with three smaller "Good" rated minicars. All three minicars were rated "Poor" in these special offset head-on car-to-car tests, while the midsize cars rated "Good" or "Acceptable".
In 2009, the IIHS celebrated its 50th anniversary and tested a 1959 Chevrolet Bel Air crashing head-on, 40% offset with a 2009 Chevrolet Malibu at 40 mph. The Bel Air's occupant compartment was extensively damaged by the crash. Coupled with the car's lack of modern safety features such as airbags and seat belts, this resulted in the crash test dummy in the Bel Air recording forces that would have probably caused fatal injuries to a real driver. This car performed far worse than the 2nd generation GM minivans that were formerly the worst performers of all time in the IIHS offset test. The Malibu's occupant compartment remained intact and advanced safety equipment protected the driver from potentially serious injury. The Malibu's crash test dummy recorded forces that would produce only a minor foot injury to a real driver.
Small overlap frontal test
On August 14, 2012, IIHS released the first results for a second, more demanding frontal offset test. The new test, which is used in addition to the 40% offset test introduced in 1995, subjects only 25% of the front end of the vehicle to a 40 mph impact. The new test is far more demanding on the vehicle structure than the 40% offset test. In the first round of test, most vehicles did poorly; only three vehicles got "good" or "acceptable" ratings.
The rating system is similar to the 40% offset, but has some key differences: hip/thigh and lower leg/foot ratings replace individual ratings for each leg and foot, and full score cannot be attained without deployment of front and side curtain airbags (due to the severe side movement often resulting from this test).
A Medical College of Wisconsin study found small-overlap collisions result in increased head, chest, spine, hip, and pelvis injuries. This sort of collision is common on two-lane roads with two-way traffic where a center median is absent. Single vehicle crashes (into a tree or a pole) account for 40 percent of small-overlap crashes. According to the IIHS, 25% of frontal crash deaths are due to small overlap crashes, with the outer front wheel first to receive the impact forces rather than the more central crash absorbing structure.
Side crash test
Compared to the NHTSA test rig, which simulates the impact from the front end of a passenger car, the taller IIHS test rig simulates the impact of an sport utility vehicle or Pickup truck (approximately a quarter of all new cars sold) into the side of the vehicle being tested. This is a very demanding test of both the vehicle's structural integrity and its side airbag systems, if any. (Seat belts play a less important role in side crashes on the impacted side of the vehicle.) While most new vehicles achieve 4–5 stars from the NHTSA (where head injuries are not part of the rating), many do not score well in the IIHS side impact test.
The IIHS assigns one of the same "Good", "Acceptable", "Marginal", or "Poor" ratings to nine categories before deciding the vehicle's overall side impact score.
IIHS began conducting vehicles tests in 2003. IIHS findings show a driver in a vehicle with a "Good" score is 70% less likely to die in a left-side crash than a driver in a vehicle rated "Poor". A 64% reduction was found for drivers in "Acceptable" rated vehicles and a 49% reduction in vehicles rated "Marginal".
Head restraint evaluation
This tests the vehicle's driver seat to determine effectiveness of the head restraints. The driver's seat is placed on a sled to mimic rear end collisions at 20 mph. Rear end collisions at low to moderate speeds typically do not result in serious injuries but they are common. In 2005 the IIHS estimated 25% of medical costs were related to whiplash injuries.
Roof strength test
In the United States rollovers accounted for nearly 25% of passenger vehicle fatalities. Features such as electronic stability control are proven to significantly reduce rollovers and lane departure warning systems may also help. Rollover sensing side curtain airbags also help to minimize injuries in the event of a rollover. In March 2009, the IIHS began testing the roof strength of vehicles.
Frontal collision avoidance evaluation
A maximum of 6 points are awarded.
The Top Safety Pick is an annual award to the best-performing cars of the year. To receive a Top Safety Pick, the vehicle must receive "Good" overall marks in the moderate overlap front, side, roof strength and seat head restraint tests, regardless of their rating in the small overlap front test because they have yet to overcome the structural reactions of a statically connected compartment.
The Top Safety Pick+ award is given to vehicles that receive good rating in at least 4 of 5 tests and no less than acceptable in the fifth test.
Past winners from 2006-on can be found on the IIHS web site.
For 2014 model year vehicles in order to receive the Top Safety Pick vehicles must be rated "Good" in the moderate overlap front, side, roof strength and head restraint tests and also be rated either "Good" or "Acceptable" in the small overlap front test. To receive the Top Safety Pick+ award the front crash prevention system must be at least "basic" and the Top Safety Pick criteria must also be met.
- Crash test
- Head injury criterion
- National Highway Traffic Safety Administration
- BeSeatSmart Child Passenger Safety Program
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- http://www.iihs.org/ratings/tsp_archive.html IIHS.org archives