NHTSA vs IIHS: The Key Differences in Crash Testing

Car shoppers often see two major safety ratings: NHTSA star ratings and IIHS Top Safety Pick awards. Jalopnik explains the differences between how each organization tests vehicles, and why one rating doesn't tell the whole story.

The National Highway Traffic Safety Administration is a government agency within the U.S. Department of Transportation. It gives vehicles one to five stars based on the likelihood of serious injury. The Insurance Institute for Highway Safety is an independent nonprofit funded by the auto insurance industry. It uses a four-tier scale (Good, Acceptable, Marginal, Poor) and awards Top Safety Pick and Top Safety Pick+ designations.

Frontal crash tests are not the same

NHTSA crashes a car head-on into a fixed barrier at 35 miles per hour. That simulates two vehicles of similar size and weight hitting each other squarely. IIHS runs an offset test at 40 miles per hour, which mimics hitting another vehicle or a fixed object like a pole at an angle. Jalopnik notes that IIHS crashes two cars per test: one on the driver's side and one on the passenger's side.

These differences matter. Jalopnik points to the 2024 Honda CR-V. Both NHTSA and IIHS gave it top overall marks, and IIHS named it a Top Safety Pick. Yet IIHS rated the CR-V Poor in its updated moderate-overlap front test, because rear-passenger protection lagged. The overall score hid that weak point.

Side impact tests also vary

NHTSA uses two side tests, Jalopnik reports. The side barrier test slams a 3,000-pound deformable barrier into the car at 38.5 miles per hour. The side pole test rolls the vehicle at 20 miles per hour into a pole just under 10 inches in diameter at a 75-degree angle. IIHS uses one side test: a 4,200-pound rig that mimics the front of an SUV strikes the car at 37 miles per hour. IIHS updated its rig after finding older tests didn't match real-world crashes.

Rollover resistance is NHTSA's territory

Jalopnik says NHTSA is the only one of the two that tests rollover risk. The agency runs a static test that compares a vehicle's track width to its center of gravity height. It also does a dynamic rollover test called the fishhook maneuver, which abruptly turns the steering to see if the vehicle lifts onto two wheels. The combined data produces an estimated rollover risk. IIHS does not test rollover resistance.

IIHS covers more than crashes

IIHS rates headlights, front crash prevention (vehicle-to-vehicle and pedestrian), seat belt reminders, and the ease of using the LATCH car seat system, according to Jalopnik. Those ratings don't measure crashworthiness, but they can help a driver avoid a crash or get the most out of safety equipment already in the car.

What it means for shoppers

A five-star NHTSA rating or a Top Safety Pick from IIHS both represent excellent performance across each organization's tests. Jalopnik notes that IIHS also has a Top Safety Pick+ level for vehicles that meet even stricter criteria. There is no single "better" rating. Looking at individual test results, rather than just the overall score, can reveal specific strengths or weaknesses that matter to you, especially if you prioritize things like pedestrian safety or easy car seat installation.

• car safety
• crash tests
• IIHS
• NHTSA
• ratings
• Top Safety Pick