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When shopping for a new car, many owners consider a vehicle’s NHTSA and IIHS safety ratings. In 2015, the National Highway Traffic Safety Administration (NHTSA) decided to review and make changes to the current rating system. These changes include the use of crash tests with specific criteria to assess cars full of passengers in different impact scenarios. So, what does a five-star rating really mean for modern vehicles?

Frontal Crash Test Details

In this test, there would be an average male-sized crash test dummy in the front driver seat and a small-sized crash test dummy in the front passenger seat. Additionally, this test represents crashes of two cars that are the same size. Moreover, during the frontal crash test, the car will crash into a structure at 35 mph.

Side Pole Crash Test

With this kind of crash test, the car is being evaluated to determine how it stands up in the event of a side pole crash. Specifically, this test generally involves the test car being positioned at a 75-degree angle. Furthermore, the car will be moved sideways into a medium-sized pole.

Insurance Institute for Highway Safety

A test dummy for crash rating determinations for the NHTSA or IIHS sits in a vehicle cabin.
Crash test dummy | Bill Pugliano via Getty Images

This is a private nonprofit organization that receives funding from auto insurance companies. The IIHS’s mode of testing is similar to that of the NHTSA although there are some differences, per U.S. News. Under this organization’s safety testing, a car’s crashworthiness can be considered good, bad, acceptable, marginal, or poor.

Moreover, the IIHS has a roof strength test that measures specific weighted resistance to simulate protection in crushing scenarios or rollovers. This crash test is accomplished by having a metal plate push along the side of the car. After assessing a vehicle’s performance, the IIHS assigns cars a top safety pick only if they pass all crashworthiness tests. As a result, safety-minded drivers should consider both the NHTSA and the IIHS safety ratings.

The Ratings Are Different Each Year

Another thing to keep in mind is that the safety ratings are not the same each year. A car that received five stars for safety last year might receive three stars this year. Alternatively, a car that received two stars a few years ago might receive four stars this year. The tests are also different nowadays, so this could be a factor in how the cars are rated for safety.

Meaning Behind the Scores

If a car gets a five-star rating, this means that there is a less than 10% chance of a serious injury. Cars with a four-star rating have an 11-20% chance of a bad injury in them. If some cars have a three-star rating, then this means that there is a 21-35% chance of a serious injury during a crash. If the car has one star, then there is a 46% chance of a critical injury.

Tips on Understanding Car Safety Ratings

Because the scores are based on competency, you won’t always be able to determine that a three-star car operates better than a four-star one. Moreover, you also won’t be able to compare ratings across different vehicle types because the ratings are based on cars in similar classes. For example, it would be difficult to compare the results of an SUV’s crash test with those of a sedan.