In the US, two separate bodies test crash safety: NHTSA (New Car Assessment Program, 1-5 star overall rating) and the insurance-funded IIHS (Good/Acceptable/Marginal/Poor ratings plus Top Safety Pick and Top Safety Pick+ awards for models that also perform well in crash-avoidance tech tests). Vehicles earning both a 5-star NHTSA rating and an IIHS Top Safety Pick+ typically represent the strongest evidence of real-world crash protection, but scores are only comparable within similar vehicle classes and model years — a 5-star compact car and a 5-star full-size SUV are not equally protective in a crash between the two.
At a glance
| Rating body | What it measures |
|---|---|
| NHTSA (NCAP) | Frontal, side, rollover crash tests; 1-5 star overall score |
| IIHS | Moderate/small overlap front, side, roof strength, head restraints |
| IIHS Top Safety Pick | Good ratings across core crash tests plus adequate headlights |
| IIHS Top Safety Pick+ | Above, plus a qualifying front crash prevention system |
Two different agencies, two different tests
NHTSA's New Car Assessment Program runs frontal, side-impact and rollover-resistance tests and issues a combined star rating from one to five, updated periodically as test protocols evolve. IIHS, funded by insurers rather than government, runs its own separate battery of tests — including the small-overlap front test that simulates hitting a pole or oncoming vehicle at the corner of the bumper — and rates each test category Good, Acceptable, Marginal or Poor rather than a single number. Because the two programs use different methodologies, a car doesn't automatically score the same on both.
What Top Safety Pick and Top Safety Pick+ actually require
To earn Top Safety Pick, a vehicle needs Good ratings across IIHS's core crashworthiness tests and at least Acceptable headlights on the trim tested — headlight quality is a bigger part of the rating than most buyers expect, since visibility failures contribute to nighttime crashes. Top Safety Pick+ adds a requirement for a front crash prevention system that performs adequately in IIHS's vehicle-to-vehicle and pedestrian test scenarios, tying the award to both structural safety and driver-assist technology working together.
Why scores aren't comparable across vehicle classes
A 5-star or Top Safety Pick+ rating measures how well a vehicle protects its own occupants and how it performs in standardized barrier tests — it does not directly measure how a car would fare in a real collision against a much larger or smaller vehicle. Mass and structural design still matter enormously in real-world crash outcomes, which is one reason both agencies rate within body-style and weight-class peer groups rather than issuing one universal ranking across all vehicles.
| Class comparison | What ratings do tell you | What they don't tell you |
|---|---|---|
| Compact car vs compact car | Reliable relative comparison | N/A |
| Compact car vs full-size SUV | Both may be 5-star | Outcome in a crash between the two, which favors mass/structure |
| Same model, different trim | Ratings can shift with different ADAS availability | Ratings sometimes apply only to specific trims tested |
Reading ratings correctly before you buy
Always check which specific trim and model year a rating applies to — automakers sometimes make mid-cycle changes to structure or safety equipment that affect only certain trims, and both agencies note this on their detailed rating pages. It's also worth checking both NHTSA and IIHS for the same vehicle, since they occasionally diverge; a car that does well on one program's specific test angles can perform less well on the other's.
A vehicle can carry a 5-star NHTSA rating from an earlier version of the test protocol that has since become tougher — always check the model year the rating applies to, not just the star count.
Beyond the headline rating
Both agencies publish detailed sub-scores (structure, restraints, driver-assist performance) on their websites, which is worth the extra few minutes versus relying on a dealer's summary of "5-star safety." For families cross-shopping SUVs, checking the second-row and child-seat-specific ratings, where available, gives a more complete picture than the front-seat-focused overall score alone.
Frequently asked questions
What's the difference between NHTSA and IIHS ratings?
Does a 5-star rating mean a car is the safest on the road?
What does IIHS Top Safety Pick+ require that Top Safety Pick doesn't?
Can two trims of the same car have different safety ratings?
How often are crash-test protocols updated?
Sources & further reading
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