Car Safety Ratings: Who to Trust and What They Mean

When searching for a new or used vehicle to purchase, safety plays a major part in the decision. Luckily, you have a selection of agencies available that rate vehicles for safety according to a variety of factors, including the National Highway Traffic Safety Administration (NHTSA), Insurance Institute for Highway Safety (IIHS), and Consumer Reports, which combines the NHTSA and IIHS ratings to develop their recommendations.

Most car safety rating organizations include a wide array of data in their testing, including front crash prevention, latch and booster seat ratings, and information on the large selection of safety features that come with most new vehicles. Some sites, such as J.D. Power, combine the ratings from multiple organizations to form their own conclusions about the safety of a vehicle.

National Highway Traffic Safety Administration (NHTSA)

The NHTSA, a government agency, created the 5-Star Safety Ratings Program through the auspices of the New Car Assessment Program (NCAP) to provide U.S. consumers with rollover safety and crash protection data for newer vehicles. This way, consumers can compare the available safety ratings to help them when purchasing a vehicle.

Originally focusing on front crash test data, the NHTSA vehicle safety ratings have grown to include side crash data, rollover resistance, and now take into account any safety technology a vehicle utilizes. With ratings available at SaferCar, the rating system was started in 1978 and provides a good resource for parents looking for vehicles safe for their kids to ride in or for teenagers to operate as they begin driving.

Insurance Institute for Highway Safety (IIHS)

IIHS ratings represent two different safety features, including technologies that help in crash avoidance and mitigation and how well a vehicle protects its occupants in an accident, also known as crashworthiness. For crashworthiness, IIHS uses a four-point rating system, including ratings of poor, marginal, acceptable, and good, for five tests: moderate overlap front, small overlap front, side, roof strength, and head restraints.

For crash avoidance and mitigation, IIHS performs track tests and rates vehicles with front crash prevention systems on a rating scale that includes basic, advanced, or superior. The IIHS also advises parents on safe vehicles for teen drivers, the best child restraint hardware, and booster seat ratings for older kids. Visit IIHS to begin searching safety information on any vehicle model.

Consumer Reports

Consumer Reports has provided unbiased product reviews since its inception in 1936 as an independent, nonprofit organization. Included in their vehicle recommendations, Consumer Reports combines car safety ratings from the NHTSA and IIHS to provide crash test and rollover data for a variety of vehicles, both old and new.

The organization also offers safety advice on a wide selection of subjects dealing with vehicle safety, ranging from the best devices on vehicles to keep you out of an accident to comprehensive guides detailing vehicle safety features. Visit ConsumerReports for many different vehicle safety ratings to help you choose the right car to keep you and your family safe on the nation's roadways.

What the Car Safety Ratings Mean

When subjecting vehicles to the various crash testing, the NHTSA and the IIHS place vehicles into a variety of classes. The NHTSA classes include passenger cars mini, passenger cars light, passenger cars compact, passenger cars medium, passenger cars heavy, sports utility vehicles, and pickup trucks and vans.

The IIHS uses a similar, though more in-depth, classification system and includes microcars, minicars, small cars, midsize cars, moderately priced cars, midsize luxury/near luxury cars, midsize convertibles, large family cars, large luxury cars, small SUVs, midsize SUVs, midsize luxury SUVs, minivans, small pickups, and large pickups.

Front-Impact Tests

But how do these institutions really know what will happen during a vehicle accident? The NHTSA and IIHS both perform frontal crash tests, though they do so in different ways. NHTSA testing uses two crash test dummies the same size as an average adult male. Researchers place the dummies side-by-side in the front seats, securing them with the vehicle's seat belts. They then crash the vehicle head on into a fixed barrier at a speed of 35 MPH.

Researchers then measure the effect the force of the impact has on the dummies and gives the vehicle a front crash test rating based on the percent chance a vehicle occupant has for sustaining a serious injury, or any life-threatening injury that requires immediate hospitalization, to the head and chest area. The five star ratings for NHTSA testing include the following:

  • 5 Stars = a 10 percent or less chance for injury
  • 4 Stars = a 11-20 percent chance for injury
  • 3 Stars = a 21-35 percent chance for injury
  • 2 Stars = a 36-45 percent chance for injury
  • 1 Star = over a 46 percent or greater chance for injury

The IIHS, on the other hand, ranks the safety of the vehicle into one of four categories: Good, Acceptable, Marginal, and Poor. Using offset testing, only one side of the vehicle's front end hits a barrier at 40 MPH. In addition to the chance of injury, IIHS testing looks for how well the structure of the vehicle holds up and the movement of the single dummy used during the test.

Side-Impact Testing

Both the NHTSA and IIHS differ in their approach to side barrier crash testing as well. Both organizations try to simulate impacts most commonly encountered in an intersection. The NHTSA crashes a deformable barrier weighing 3,015-pounds into the test vehicle while two test dummies — the same size as an average man — sit buckled into the front two seats. Researchers measure the force of the impact to the head, neck, chest, and pelvis and rate it on a scale from 1 to 5 stars as follows:

  • 5 Stars = 5 percent or less chance for injury
  • 4 Stars = 6-10 percent chance for injury
  • 3 Stars = 11-20 percent chance for injury
  • 2 Stars = 21-25 percent chance for injury
  • 1 Star = 26 percent or greater chance for injury

The difference between the NHTSA and the IIHS test can be found in the size of the barrier and dummies used, as well as what the test is designed to measure. Using the Good, Acceptable, Marginal, and Poor rating system, the test measures the injuries that can happen to small women or children in a side impact from a large truck or SUV. More severe than NHTSA testing, the test helps the IIHS to evaluate a vehicle’s side-impact protection potential, allowing them to find and recommend vehicles that can give this type of protection.

Rollover Testing

Another major area of testing includes rollover tests. The NHTSA represents the only group that currently performs this type of testing. Using dynamic testing combined with static tests, researchers look at the likelihood of a vehicle to rollover in a number of real-world situations.

The test vehicle simulates a vehicle containing five passengers and a tank of gas. Driven in a manner meant to simulate an emergency lane change, testing equipment measures how far the tires come off the ground. A tip occurs when at least two of the tires come at least two or more inches off the ground. The vehicle garners a star rating depending on the percentage chance of a rollover taking place as per the following:

  • 5 Stars = 10 percent chance for rollover
  • 4 Stars = 10-20 percent chance for rollover
  • 3 Stars = 20-30 percent chance for rollover
  • 2 Stars = 30-40 percent chance for rollover
  • 1 Star = 40 percent chance for rollover

Who Can You Trust?

When it comes to vehicle safety ratings, both the NHTSA and the IIHS represented trustworthy sources of vehicle safety testing. And even though they both approach different tests in slightly different ways, their knowledgeable approach and use of test dummies to determine the force of impacts from a variety of directions make their findings that much more compelling, especially when taken in the context of finding the safest vehicle to drive on the road.

Organizations such as Consumer Reports put enough trust in both the NHTSA and the IIHS to include their test results as a part of their own vehicle safety recommendations.

The Importance of Performing an Inspection of a Vehicle Before Buying

Before buying a vehicle, ask YourMechanic to perform an inspection to determine the vehicle’s overall condition, including roadworthiness and safety. The mechanic should also determine whether the vehicle shows any signs of needing repairs to important vehicle functions such as the tires, brakes, or suspension. This extra step helps you make a more informed decision about the safest vehicle to buy. Make sure to take into account the available safety ratings, looking for vehicles with the best crash test and rollover ratings.


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