IIHS Rating Categories at a Glance: Good, Acceptable, Marginal, and Poor

What the Four IIHS Rating Tiers Mean

The Insurance Institute for Highway Safety (IIHS) evaluates vehicles across a series of standardized crash and safety tests, assigning one of four ratings to each category: Good, Acceptable, Marginal, or Poor. These are not subjective labels — each rating corresponds to precise, measurable outcomes observed during controlled testing.

Here is what each tier represents in practice:

• Good: The vehicle performed well across all measured criteria for that test. Structural integrity was maintained, occupant injury measures fell within low-risk thresholds, and geometry — such as door sill intrusion or head restraint position — met IIHS benchmarks.
• Acceptable: Performance was solid but not optimal. One or more secondary measures fell slightly outside ideal ranges, though primary injury risk indicators remained low. Think of it as a minor deduction, not a safety failure.
• Marginal: The vehicle showed meaningful weaknesses — elevated injury risk metrics, moderate structural deformation, or inadequate restraint performance. A Marginal rating in a key area warrants careful consideration.
• Poor: Significant safety deficiencies were identified. Structural collapse, high injury-risk sensor readings, or severe restraint failures define this tier. Vehicles rated Poor in critical tests may pose substantially greater risk in comparable real-world crashes.

For a broader perspective on how IIHS ratings compare to NHTSA's star-based system, see how the two rating systems differ.

The Tests Behind Each Rating

IIHS does not issue a single overall score. Instead, it rates vehicles separately across distinct test categories. Understanding which tests produced which ratings is essential to reading a scorecard accurately.

Core IIHS test categories include:

• Small Overlap Front (driver and passenger side): A 40 mph barrier test covering only 25% of the vehicle's front end. This replicates real-world corner impacts and is one of the most demanding evaluations in the program.
• Moderate Overlap Front: A 40 mph test covering 40% of the vehicle width. It was the first frontal test IIHS introduced and remains a baseline measure.
• Side (Updated): A moving deformable barrier test redesigned in 2021 with a heavier, taller barrier to better represent modern SUV-to-car crash dynamics.
• Roof Strength: A crush resistance test simulating rollover scenarios. The ratio of peak force to vehicle weight determines the rating.
• Head Restraints and Seats: Evaluates whiplash protection in rear-end collisions using geometric analysis and dynamic sled tests.
• Headlights: Rated separately for each trim and lighting configuration. A vehicle can earn Good on crash tests but Poor on headlights — a detail many shoppers overlook.
• Vehicle-to-Vehicle and Vehicle-to-Pedestrian Front Crash Prevention: Tests automatic emergency braking (AEB) systems at varying speeds and scenarios.

Each category rating stands independently. A vehicle might earn Good in five categories and Marginal in one. That single Marginal rating is worth examining — particularly if it falls in a high-frequency crash type. See why the same car can score differently across programs for additional context.

Reading a Full Scorecard in Seconds

IIHS publishes complete vehicle scorecards at iihs.org. Here is how to extract what matters quickly:

1. Identify the model year and trim: Ratings apply to specific production years and sometimes specific trim levels or build dates. Mid-cycle safety changes can alter results.
2. Scan for any Poor or Marginal ratings first: The four-tier system makes outliers easy to spot. Start by looking for where the vehicle underperformed rather than where it excelled.
3. Check headlights separately: IIHS lists headlight ratings by trim and option package. A base-trim vehicle and a higher-trim variant may carry different headlight ratings even with identical crash test results.
4. Note the front crash prevention rating: AEB systems are rated on a separate track. A vehicle can earn Good on passive crash tests but Basic or No Credit on active prevention — a meaningful distinction for everyday risk reduction.
5. Look for Top Safety Pick designations: TSP and TSP+ awards require a combination of Good or Acceptable crash ratings plus Good or Acceptable headlights. The award criteria evolve annually. For more on what those labels actually guarantee, see what a Top Safety Pick label does and doesn't mean.

For guidance on applying these ratings to specific segments, reading a sedan's safety rating walks through how scorecard interpretation changes by vehicle type. And if you are evaluating a used vehicle, the used car evaluation hub explains how safety ratings factor into broader condition and history assessments.