What the safety ratings actually measure

New car safety ratings come from two independent sources: the National Highway Traffic Safety Administration (NHTSA) and the Insurance Institute for Highway Safety (IIHS). They test different things in different ways, so a car's rating from one source does not automatically match the other.

NHTSA runs crash tests and rates cars on a scale of one to five stars. A five-star rating means the car performed better than average in that particular test. IIHS uses a different scale—Good, Acceptable, Marginal, or Poor—and also awards an overall rating of Top Safety Pick if a car meets their threshold across multiple tests. Neither organization tests every model, and neither updates ratings every year, so the year of the test matters.

Both organizations publish their results free online. NHTSA's ratings appear at safercar.gov, where you can search by model year and vehicle name. IIHS ratings are at the Insurance Institute's website, organized by vehicle class. You do not need to pay anyone to see these ratings.

Key Takeaways

  • NHTSA and IIHS test different crash scenarios and use different rating scales, so check both sources rather than relying on one.
  • A five-star NHTSA rating means above-average performance in that specific test, not that the car is the safest possible.
  • IIHS's Top Safety Pick award requires meeting thresholds across multiple crash tests, not just one.
  • Ratings are tied to specific model years and sometimes specific trim levels, so verify the exact year and configuration you are considering.
  • Newer model years may not have ratings yet, because testing takes time; older ratings do not automatically apply to redesigned models.

How NHTSA's five-star system works

NHTSA tests five crash scenarios: frontal crash, side crash, rollover, front crash prevention, and side crash prevention. Each test gets its own one- to five-star rating. The overall rating you see is an average of these five scores, rounded to the nearest half-star.

A five-star rating in one test means the car performed better than 95 percent of vehicles tested in that scenario. A one-star means it performed worse than 95 percent. Three stars is average. The tests use crash dummies and measure injury risk to the head, chest, and legs. NHTSA publishes the detailed injury scores alongside the star rating, so you can see which body parts the car protects well and which it does not.

The rollover test does not involve an actual crash—it measures the vehicle's resistance to tipping based on its height, weight, and center of gravity. A tall SUV will naturally score lower on rollover resistance than a sedan, even if both are well-designed, because the physics work against it. This is why comparing ratings across different vehicle types can be misleading.

How IIHS ratings differ from NHTSA

IIHS runs six crash tests instead of five, and they test at higher speeds in some cases. Their tests include frontal crash, side crash, rollover, rear crash, crashworthiness (how well the car protects occupants), and crash avoidance (how well the car prevents a crash from happening). Each test is rated Good, Acceptable, Marginal, or Poor.

IIHS also awards a Top Safety Pick designation to vehicles that earn Good or Acceptable ratings across all crashworthiness tests and meet a crash avoidance threshold. A Top Safety Pick+ (with a plus sign) requires an even higher crash avoidance score. These awards are more selective than NHTSA's five-star rating—fewer vehicles earn them, and earning one is a stronger signal of above-average protection.

IIHS tests fewer vehicles than NHTSA, so your car may have an NHTSA rating but no IIHS rating, or vice versa. The organization prioritizes testing popular models and new designs. If a model has not been tested by IIHS, that does not mean it is unsafe—it means IIHS has not evaluated it yet.

Why the same car can have different ratings from each source

NHTSA and IIHS use different crash speeds, different impact angles, and different dummies with different sensors. A car that scores well on NHTSA's frontal crash test at 35 miles per hour might score differently on IIHS's frontal crash test at 40 miles per hour. The tests are designed to measure real-world safety, but they measure different real-world scenarios.

A car can also earn a five-star NHTSA rating overall while failing to earn IIHS's Top Safety Pick award. This happens when the car performs well on NHTSA's tests but does not meet IIHS's higher thresholds or does not score well enough on crash avoidance. Neither rating is wrong—they are measuring different things with different standards.

For this reason, the most useful approach is to look at both ratings and read the detailed breakdowns. If a car scores well on both, that is a strong signal. If it scores well on one but not the other, dig into the specific test results to understand where the difference lies.

What model year and trim level matter

Safety ratings are specific to a model year. A 2024 Honda Accord's rating does not automatically apply to a 2023 Accord, even though they look similar. Manufacturers change crash structures, airbag systems, and materials between model years, and those changes affect how a car performs in a crash.

Some ratings also vary by trim level or body style. A sedan version of a car might have a different rating than the wagon or hatchback version of the same model, because the structure is different. When you search for ratings, make sure you are looking at the exact year and body style you are considering.

If a model has been recently redesigned, the old rating no longer applies. NHTSA and IIHS test the new design separately. During the gap between the old design's rating and the new design's test results, you may have no recent rating to reference. In that case, you can look at the previous generation's results as a rough guide, but do not assume they carry over.

How to use ratings when comparing vehicles

Start by checking both NHTSA and IIHS for the specific model year you are considering. Write down the overall ratings and note which tests the car performed well on and which it did not. If one source has not tested the model, note that too.

Compare vehicles in the same class—sedan to sedan, SUV to SUV—because the physics of different vehicle types make direct comparison difficult. A five-star SUV is not necessarily safer than a four-star sedan in a real crash, because the SUV's weight and size give it advantages that ratings do not fully capture.

Read the detailed test results, not just the overall rating. A car might earn a five-star overall rating but score poorly on side crash protection, which is important to you. The detailed breakdowns let you weight different tests according to your priorities. If you drive mostly on highways, rear crash and rollover resistance might matter more than city crash scenarios.

Remember that ratings measure how well a car protects occupants in a crash, not how well it avoids crashes. A car with a high crash avoidance score (from IIHS) is less likely to crash in the first place. A car with high crashworthiness scores protects you better if a crash does happen. Both matter, and they measure different things.

What ratings do not tell you

Safety ratings do not measure reliability, repair costs, or how often a car breaks down. A car can have excellent crash test ratings and still have expensive transmission problems or electrical gremlins. Check reliability data separately—J.D. Power, Consumer Reports, and manufacturer warranty claim data all offer different perspectives on how often cars need repairs.

Ratings also do not account for driver behavior, road conditions, or the other vehicle involved in a crash. A car with a five-star rating will not protect you if you are driving recklessly or if you collide with a much heavier vehicle at high speed. Safety ratings assume a baseline level of driver competence and typical crash scenarios.

Finally, ratings do not measure features like blind-spot monitoring, lane-keeping assist, or automatic emergency braking in isolation. IIHS does measure crash avoidance as a category, but individual safety features are not rated separately. If a specific feature matters to you, check whether the car offers it and read reviews of how well it works in practice.

Frequently Asked Questions

Is a five-star NHTSA rating the same as IIHS's Top Safety Pick?

No. A five-star NHTSA rating is an average across five tests; a car can earn five stars overall while scoring three stars on one test. IIHS's Top Safety Pick requires Good or Acceptable ratings on all crashworthiness tests, which is a higher bar. A car with five stars from NHTSA might not have earned Top Safety Pick from IIHS.

Can I trust an older model's rating if the new model year has not been tested yet?

Older ratings give you a rough sense of how the manufacturer designs for safety, but they do not apply directly to a redesigned model. If the new model has been significantly changed, the old rating may not reflect its actual performance. Check the manufacturer's website or press releases to see what changed, and wait for new test results if possible.

Why do SUVs and sedans have different average ratings?

SUVs are taller and heavier, which makes them more resistant to rollover in some scenarios but more prone to it in others. Their weight gives them an advantage in frontal crashes but can increase injury risk in side crashes. Ratings account for these differences, but comparing a five-star SUV to a four-star sedan does not mean the sedan is less safe overall.

Do safety ratings include things like lane-keeping assist or automatic emergency braking?

IIHS measures crash avoidance as a category, which includes how well a car's systems prevent crashes. NHTSA also tests front crash prevention. However, these are separate from crashworthiness ratings. If you want to know how well a specific feature works, read owner reviews and test drive the car yourself to see how responsive the system is.

What if a car I am considering has no safety rating from either source?

Some vehicles, especially newer models or less common vehicles, have not been tested yet. In that case, look at ratings for similar vehicles from the same manufacturer, check owner forums for real-world crash reports, and review the car's warranty coverage for structural and safety components. You can also contact the manufacturer directly to ask about their safety testing.