What Do Car Safety Ratings Mean?
Here’s a look at the organizations that give the ratings and how those ratings are achieved
Vehicle safety ratings are one of the most important concerns for consumers considering a new vehicle purchase. A vehicle with a high safety rating gives drivers the peace of mind that they and their passengers will be kept safe in the event of a collision, a rollover, or other accident. But what actually goes into a “5-Star Safety Rating” rating or “Top Safety Pick,” and what kind of organizations give out these ratings? We break it down for you.
How are vehicles tested and rated?
Two nonprofit authorities in the US rate vehicles for safety each year: the National Highway Traffic Safety Association (NHTSA) and the Insurance Institute for Highway Safety (IIHS). Each has adapted test programs that vary slightly but together provide a comprehensive analysis of a vehicle’s inherent safety.
What’s behind IIHS ratings
The IIHS is an independent nonprofit organization focused on reducing deaths, injuries, and property damage from vehicle crashes. Together with the Highway Loss Data Institute, the IIHS also leverages insurance data to publish loss results by vehicle make and model.
Currently, the IIHS evaluates crashworthiness through a series of crash-impact tests on the front and sides of a vehicle. For frontal tests, vehicles are accelerated into a barrier in either a "moderate overlap" or "small overlap" test. In overlap tests, only a portion of the front of the vehicle contacts the barrier. Tests are performed on both the driver’s side and passenger side of each vehicle. Overlap tests are valuable because they allow the IIHS to evaluate how far into the passenger compartment objects intrude in a controlled crash, providing a better picture of how protective a vehicle’s structure is.
Side-crash tests involve accelerating a moving barrier into the driver’s side and passenger side of vehicles to determine their rating. The IIHS has adapted their barrier, making it taller, to account for the increased number of taller SUVs and trucks on the road.
The IIHS also assesses vehicles for a range of safety features, including a headlight evaluation, front crash prevention, and, starting in 2022, seat belt reminder evaluation. Seat belt reminder tests evaluate a vehicle on its alarms, reminders, and alarm triggers that notify occupants to buckle up. Seat belt systems are rated either good, acceptable, marginal, or poor.
What’s behind NHTSA ratings
While the IIHS is an independent organization, NHTSA is a government organization dedicated to enforcing vehicle performance standards through partnerships with state and local governments and by working closely with automobile manufacturers. NHTSA performs three types of crash test and a rollover resistance test, giving vehicles ratings from one to five stars.
NHTSA does not perform overlap collision tests and instead performs full-width crash tests and a side-pole crash test. In the frontal crash test, vehicles are accelerated to 35 miles per hour into a fixed barrier. Side-impact tests accelerate a 3,000 pound barrier to just over 38 miles per hour into the side of a stopped vehicle. A side-pole crash test pulls a 25-centimeter diameter pole at 20 miles per hour into the driver’s seating location at a 75-degree angle.
While these tests are less demanding in terms of object intrusion into the passenger cabin, they tend to send stronger forces through seat belts and airbags, demanding more from them.
New technology continues to make vehicles safer
Safety features like airbags, antilock brakes, and daytime running lights, which have been introduced over the last 20 to 30 years, provide additional protection during a crash or even help drivers avoid crashes altogether. And over the last decade, innovations such as blind spot monitors, lane keeping assistance, automatic emergency braking, and adaptive cruise control are serving to keep motorists even safer on the roadways.
As safety technologies continue to advance become standard in vehicles, the IIHS and NHTSA will need to evolve their testing methods and criteria accordingly to provide meaningful ratings for car buyers.