Understanding NHTSA and IIHS Crash Tests
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Understanding NHTSA and IIHS Crash Tests

Vehicles are repairable after an accident, but physical injuries can be costly and difficult to recover from. How do you know which vehicle is safest? Here’s what you need to know to understand NHTSA and IIHS crash test results.


The National Highway Traffic Safety Administration (NHTSA) is a government agency that started testing vehicles for frontal impact protection using crash test dummies in 1978, followed by side impact tests in 1996 and rollovers in 2000. In 2010, they started adding recommended safety technologies alongside their 5 Star Safety Ratings, pushing automakers to adopt systems that they’ve proven can reduce the chance of injury in an accident or avoid accidents altogether: through these efforts, rearview cameras have become standard across all vehicles for the 2018 model year and automatic emergency braking systems will be adopted industry-wide by 2022.

NHTSA Testing

The agency completely overhauled their rating system for the 2011 model year, so cars given a 5-star rating the previous year may earn as little as three stars under the new system. This revision switched from 50th percent tile male dummies (5 foot 9.1 inches and 172 lbs.) to a 5th percent tile female dummies (5 foot 2 inches and 110 lbs.) and added more sensors to measure impacts across the body. They perform three crash tests:

The front crash test sends the vehicle into a wall at 35 mph, measuring forces in two dummies sitting in the front seats and wearing seat belts.

The side crash test simulates a car weighing 3,015 lbs. traveling 38.5 mph hits the left side of the vehicle.

The side pole and rollover test simulate accidents that happen when the car is out of control. The side pole crash test pulls the vehicle into a 25 cm-wide pole at a 75-degree angle at 20 mph, while the rollover test simulates a sharp turn at 55 mph.


The Insurance Institute for Highway Safety is an independent research organization backed by insurance companies. They test vehicles to provide data that helps automakers design cars that reduce losses from crashes including deaths, injuries and property damage.

IIHS Testing

The IIHS introduced the moderate overlap test in 1995 and the driver-side small overlap frontal test in 2012 to simulate real-world crash conditions. The moderate overlap test uses a crushable aluminum honeycomb block to simulate an impact with another vehicle, while the small overlap test uses a rigid barrier to simulate a telephone pole. In both tests, the vehicle hits a wall at 40 mph. Both tests use a Hybrid III crash test dummy, an updated version of the 50th percent tile male doll the NHTSA used to use, in the driver’s seat.

After noticing differences in driver and passenger-side crash structures, the IIHS introduced the passenger-side small overlap frontal test for 2017 models. This is identical to the driver-side test except the impact is on the passenger side, and there are dummies in both the driver and passenger seats.

The IIHS’s side impact test uses the same basic parameters as the NHTSA test including the use of 5th percent tile female dummies, but the simulated vehicle is taller, weighs 3,300 lbs. and hits the car at 31 mph to simulate an impact with a truck or SUV.

Understanding the Ratings

The NHTSA rates vehicles from 1-5 stars for specific categories, while the overall rating is weighted more toward front end impacts since these are more common. They also note if the vehicle has recommended safety technologies including automatic braking, a reverse camera, lane departure warning and forward collision warning.

The IIHS rates test good, acceptable, marginal and poor. An IIHS Top Safety Pick has “Good” ratings in all tests, while “Top Safety Pick +” also gets an “acceptable” or “good” in a recently added test for headlight brightness and visibility. As automakers have time to modify their vehicles to perform better in the headlight test, it will become part of the standard Top Safety Pick tests.

Both organizations revise their test requirements periodically and change the results of older vehicles to reflect this. This doesn’t mean an older vehicle is suddenly less safe, it’s just not as safe as a newer vehicle.

Restoring the Safety of Your Vehicle

Merton Auto Body is an I-CAR Gold Class certified shop, and our staff is ASE certified, letting us provide top quality collision repair so your vehicle will be just as safe as it was before an accident. Getting this quality doesn’t have to take longer, either: our Autobody Estimating Center can get work approved by your insurance company faster, so the car can be fixed and back in your hands sooner. To learn more, visit MertonAuto.com.


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