What is an NHTSA Safety Rating? Your Questions Answered

If you’ve purchased a car in the last 15 years, there’s a good chance you’ve read safety ratings from the NHTSA, even if you didn’t seek them out. Why? Because as of 2006, it’s been required that new car window stickers include them, alongside the fuel economy and pricing information you’re used to.

Cars tested by the NHTSA receive ratings out of five stars in three categories, plus an overall safety rating. The more stars a vehicle earns, the lower the chance of injury to its occupants in the case of a crash. What does it take for a car to earn a five-star safety rating? That’s what we’re here to find out.

What Is the NHTSA?

The National Highway Traffic Safety Administration is a government agency that falls under the Department of Transportation. It was established as part of the Highway Safety Act of 1970 to reduce deaths, injuries, and economic losses from vehicle collision, and it began frontal crash testing in 1978.

The NHTSA’s crash-testing program has come a long way since then. Today, in addition to frontal crash testing, it evaluates vehicles in side barrier and side pole collision tests, and performs a rollover resistance test. The most recent addition to its protocol is a section for recommended safety technologies that have been verified to meet the NHTSA’s performance criteria.

NHTSA Front Crash Testing

Unlike the small overlap front tests conducted by the IIHS, the NHTSA’s frontal crash test is intended to simulate a head-on crash with another vehicle of identical size and weight. (The example shown is a driver travelling the opposite direction veering into your lane.)

The test is conducted with a crash dummy representing an average-size adult male in the driver’s seat and another representing a small adult female in the passenger seat, both secured with the vehicle’s installed seatbelts.

NHTSA testing methodology dictates that the vehicle be crashed into a fixed barrier at 35 mph. Based on data drawn from sensors in the dummies’ heads, necks, chests, and legs, analysts determine the likelihood of injury for the driver and passenger in the event of a crash. Vehicles most likely to protect their passengers from injury earn five-star ratings. Ratings can only be accurately compared between vehicles of the same class and weight, give or take 250 pounds, so test results for the shrinking segment of small, light cars are becoming increasingly irrelevant.

NHTSA Side Crash Testing

The NHTSA conducts two separate tests to evaluate a car’s crashworthiness in the event of a side collision, the first being the side barrier test. For this evaluation, the testing parameters try to simulate a car driving through a four-way intersection and being T-boned on the driver’s side by another vehicle.

The average male dummy remains in the front seat, and the small female dummy is moved to the driver’s side rear seat. Conducting the test involves a 3,015-pound barrier moving at 38.5 mph and colliding with the stationary test vehicle. Readings are taken from the head, chest, abdomen, and pelvis of both dummies to determine the likelihood and severity of injury. The NHTSA assigns three ratings for driver, rear passenger, and combined.

On the other side of things, a side pole crash test is utilized to simulate losing grip on a low-friction surface (such as a wet or snowy street) and colliding with a telephone pole on the driver’s side. The test is conducted only with the small female dummy in the driver’s seat. Angled at 75 degrees, the vehicle is pulled sideways into a 9.8-inch diameter pole at the driver’s seating location.

For the side pole test, measurements are taken from the sensors in the dummy’s head, chest, lower spine, abdomen, and pelvis. A vehicle’s side pole and side barrier test scores contribute to combined side ratings for the front and rear seat, which in turn combine to make the overall side rating. Unlike front crash ratings, all side-impact test scores can be compared with those of any other vehicle.

NHTSA Rollover Testing

The scenario the NHTSA intends to replicate with this test is an SUV travelling at 55 mph that encounters a sharp curve, is unable to slow down, departs the road, and rolls over. Rollover testing was added to the NHTSA’s gamut of testing in 2000, based on data that suggests that rollovers represent 35 percent of fatal crashes.

Rollover ratings are based on an at-rest lab measurement, internally known as the Static Stability Factor, which analyzes a vehicle’s weight distribution and center of gravity. The SSF, combined with the results of an aggressive driving maneuver that evaluates a car’s vulnerability to tipping, are what determine the rollover rating.

Driver Assistance Technology

Since 2010, the NHTSA’s ratings have also included a list of recommended driver-assist active safety features. Whereas those systems were reserved for high-end luxury cars a decade ago, affordable cars like the Toyota Corolla and Honda Civic now feature a suite of standard active safety tech, even on entry-level trims.

These recommendations do not impact a car’s overall safety rating and are completely unrelated to the five-star rating system. Rather, they intend to highlight a vehicle’s active safety features—such as lane keep assist, automatic emergency braking, or adaptive cruise control—while detailing whether those features are standard or optional and pointing out features missing from a model.

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