NHTSA vs. IIHS crash tests: what the ratings actually mean
When you shop for a safe used car you'll see two very different safety badges: NHTSA's 5-star rating and the IIHS Top Safety Pick. They are not the same test, the same scale, or even the same organization. Here's what each one measures, why a car can earn one and miss the other, and how to use both.
The short answer
NHTSA is the U.S. government's 5-star program (it's the rating we show on our safety pages). IIHS is a separate insurance-industry nonprofit with tougher, more specific tests and its "Top Safety Pick" awards. They test differently, so check both — the genuinely safe cars do well in each.
Who runs each program
- NHTSA — the National Highway Traffic Safety Administration, a U.S. federal agency. Its New Car Assessment Program (NCAP) produces the familiar 1-to-5 "star" ratings. This is government data, and it's the rating VinSleuth surfaces from the official source.
- IIHS — the Insurance Institute for Highway Safety, an independent nonprofit funded by auto insurers. It runs its own crash and crash-avoidance tests and gives out "Top Safety Pick" and the higher "Top Safety Pick+" awards.
Both are credible. They exist side by side because insurers wanted tougher, more targeted tests than the federal minimum — so IIHS often pushes the industry on crashes the star program doesn't isolate.
What each one tests
The tests overlap but are far from identical:
| Area | NHTSA (5-Star / NCAP) | IIHS |
|---|---|---|
| Frontal crash | Full-width frontal into a rigid barrier | Moderate-overlap and small-overlap front (driver & passenger side) |
| Side crash | Side barrier + side pole | Updated, more severe side-impact test |
| Rollover | Rollover resistance (tip-over risk) | Roof-strength test |
| Crash avoidance | Recommended advanced tech noted | Front crash prevention rated; headlights graded |
| Result format | 1–5 stars (overall + by direction) | Good / Acceptable / Marginal / Poor → award tiers |
The biggest practical difference is the small-overlap front test (where only the front corner of the car hits the barrier) and headlight grading — both IIHS specialties that the star program does not isolate. That's why a car can earn five NHTSA stars yet only a middling IIHS result.
Why the two ratings disagree
- Different tests, different scales. Five stars is not the same yardstick as "Top Safety Pick+." Each program weights crashes its own way.
- Different vehicles tested. NHTSA rates a broad set of body styles and drivetrains; IIHS concentrates its testing, so many trims simply aren't IIHS-rated. A missing award isn't a failing grade.
- Ratings are configuration-specific. Both programs test particular builds. A rating may apply to one body style or model year and not another — which is also why our safety pages note when an exact configuration isn't rated.
- Standards tighten over time. Both organizations raise the bar; a 2018 award and a 2022 award are not the same achievement.
How to use both when buying used
- Start with the NHTSA stars for the exact year/make/model — look them up free here. They're easy to compare across almost every car.
- Then check the IIHS result for that specific model year on the IIHS site. Look especially at the small-overlap front and side tests, and whether it earned Top Safety Pick.
- Favor cars that do well in both programs — that's the strongest signal of real-world crash protection.
- Don't stop at the badge: also scan open recalls and owner complaints, since a safe-by-design car can still have an unrepaired defect.
A note on what ratings can't tell you
Crash ratings measure how a vehicle performs in standardized tests, not how a specific used car has been maintained, repaired, or damaged. A 5-star car that's been in a poorly-repaired collision is not a 5-star car anymore. Pair the ratings with the VIN checks — decode the VIN, confirm the spec, check recalls — and, if you need accident or title history, a paid NMVTIS report. Ratings tell you about the model; the VIN and an inspection tell you about the actual car.