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Automotive Safety / Crash Testing Explained

Posted on May 10, 2013

Car manufacturers often tout in their advertising that a particular model has received “five stars” from a particular safety agency and thus that such car model is very safe.  While obtaining a good rating from any particular agency is welcome, it does not necessarily mean that a car is overall as safe as or safer than its competitors.  This is because there are in fact several different safety agencies and each conducts a different variety of crash tests.  It is very common for a car model to receive strong scores in one test from an agency while the very same model receives mediocre scores from another agency because of variances in the crash tests.  Car Match follows crash testing by all major European and US agencies and will properly advise you in your report as to which models truly offer the best safety.

To help you better understand the crash tests conducted by the various agencies, Car Match has summarized the crash test protocol for each agency below.

    Insurance Institute for Highway Safety (IIHS Official Website) – The IIHS is a non-profit organization funded by auto insurers that works to reduce the number of vehicle crashes and the rate of injuries and property damage when they occur.  The IIHS conducts a variety of crash tests, including the Moderate Offset Impact Test, Small Overlap Offset Test, Side Impact Test, Roof Strength Evaluation and Rear Crash Protection Test and assigns ratings of “Good”, “Acceptable”, “Marginal” and Poor.”

    Moderate Offset Impact Test – This test is a frontal crash test conducted at 40 mph in which the car impacts a deformable barrier at an offset of 40% of the car’s width.  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. Many real-life frontal impacts are offset.

    Small Overall Offset Test – This test is similar to the Moderate Offset Impact Test, only 25% of the car’s width is exposed versus 40%.  The new test is far more demanding on the vehicle structure than even the Moderate Impact Offset Test, and many previously excellent performers from luxury manufacturers did poorly.  The test is relatively new and was devised to address the increases that IIHS has seen in “sideswipe” frontal impacts as a result of greater driver distraction due to cell phones, texting, etc.

    Side Impact Test – In this test, a simulated pickup or SUV (as opposed to a car, as in the NHTSA NCAP test) impacts the side of a vehicle at 31 mph.

    Roof Strength Evaluation – In this test, a metal plate is pushed against one side of a roof at a constant speed. To earn a good rating, the roof must withstand a force of 4 times the vehicle’s weight before reaching 5 inches of crush.

    Rear Crash Protection Test – This test uses the vehicle’s driver seat in order to determine the effectiveness of the head restraint. 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.

    National Highway Traffic Safety Administration New Car Assessment Program (NHTSA Official Website) – The NHTSA is US government agency that works to reduce vehicle crashes and prevent crash-related injuries.  The NHTSA conducts a variety of crash tests as part of its New Car Assessment Program, including the Frontal Impact Test, Side Impact Test, Side Pole Test and Rollover Test and assigns ratings of one to five stars.

    Frontal Impact Test – In this test, the car is crashed into a fixed barrier at 35 mph.  This test provides more rapidly deceleration than does the IIHS’s Moderate Offset Impact Test, but does not stress the car’s structure as much as the IIHS test.

    Side Impact Test – In this test, a simulated car (versus a higher pickup / SUV in the IIHS test) coming at an oblique angle impacts the side of a standing vehicle at 38.5mph.

    Side Pole Test – In this test, the test vehicle impacts sideways (at a 75 degree angle) into a 25-cm pole at 20 mph.  The test mimics crashing into a narrow object like a utility pole or tree and severely stresses a car’s body structure.

    Rollover Test – In this test, the test vehicle is tilted until it rolls over.  This test measures the likelihood of a vehicle to roll, versus the strength of its roof once it has rolled, as does the IIHS’ Roof Strength Evaluation.

    European New Car Assessment Program (Euro NCAP Official Website) – The Euro NCAP is a performance program based in Belgium funded by European governments.  Euro NCAP conducts a variety of crash tests as part of its program, including the Frontal Impact Test, Side Impact Test, Pole Side Impact Test, Child Protection Test, Pedestrian Protection Test and Whiplash Test and assigns ratings of “Good”, “Adequate”, “Marginal”, “Weak” and “Poor.”

    Frontal Impact Test – This test is virtually identical to the IIHS’ Moderate Offset Impact Test and is a frontal crash test conducted at 40 mph in which the car impacts a deformable barrier at an offset of 40% of the car’s width.  As with the IIHS’ test, this test shows the car’s structural strength better than the NHTSA’s full-width testing does.

    Side Impact Test – In this test, a simulated car (versus a higher pickup / SUV in the IIHS test) impacts the side of a standing vehicle at 31mph.

    Pole Side Impact Test – In this test, the test vehicle impacts sideways (at a 90 degree angle) into a narrow pole at 18 mph. As with the NHTSA’s pole test, this test mimics crashing into a narrow object like a utility pole or tree and severely stresses a car’s body structure.

    Child Protection – Unlike either the IIHS or NHTSA, Euro NCAP conducts each of the above tests with a rear-facing baby seat and front-facing booster seat in place in the rear seats and provides ratings as to how children in such seats would fare in such accidents.

    Pedestrian Protection –Euro NCAP conducts a series of crash tests in which the test vehicle impact both child and adult pedestrians and assesses how the car protects such pedestrians.

    Whiplash – Euro NCAP tests the seats and headrests of test vehicles in a rear impact scenario and assigns ratings as to how such vehicles protect from whiplash.

In all cases, when comparing crash test scores, it is important to only compare scores amongst vehicles of fairly similar weight (within 200 lbs).  As a result of simple physics, heavier cars have a substantial advantage over lighter cars in terms of protecting their occupants.  Very simply, in a head on collision at identical speeds, between a 5000lb car and a 2500lb car, the impact forces on the passengers in the smaller car will be 4x as great.  Thus, a two-star rated SUV can offer better occupant protection than a five-star rated sub-compact if they collide with each other head-on.

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