IIHS Finds Definitive Link Between High Crash Scores And Lower Fatality Risk

Crash / 4 Comments

These findings underline the importance of crash-safety scores for new cars.

The Insurance Institute for Highway Safety (IIHS) has found a clear link between higher crash safety ratings and a reduced risk of dying in a real-world crash, specifically with regard to the driver-side small overlap front crash test.

While it is logical that higher safety ratings from agencies like the IIHS and NHTSA will result in a safer car, the link between these ratings and real-world crashes is rarely evaluated, where the circumstances are often different to crash tests conducted in controlled environments with crash-test dummies.

The study found that a driver in a vehicle rated Good for the driver-side overlap front crash test was 12% less likely to die in a front crash than a driver in a vehicle rated Poor for the same test. These findings come soon after the IIHS implemented tougher criteria for its crash tests, reducing the number of new cars qualifying for the authority's vaunted Top Safety Pick and Top Safety Pick Plus awards.


To find out how crash-test ratings correlated with real-world crashes and fatalities, researchers identified the make, series, and model of vehicles involved in frontal crashes between 2012 and 2020. This was done using proprietary VIN-decoding software from the IIHS-affiliated Highway Loss Data Institute. This data was cross-referenced with IIHS results from driver-side small overlap crash ratings. Using police reports, researchers could determine the number of driver deaths in frontal crashes.

The driver-side small overlap front crash test was added to the IIHS testing regimen in 2012 when it was determined that these crashes accounted for a quarter of frontal collisions where the driver was seriously injured or killed. That's a high enough percentage for automakers to take these types of crashes seriously, especially since we're decades away from a goal of zero accident fatalities.


The small overlap tests involve just 25% of the vehicle width and are designed to simulate what happens when a car collides with another car or objects like trees or utility poles. The test is more difficult than others since there isn't a direct impact with the frame rail of the vehicle, so the energy of the impact must mostly be absorbed by the occupant compartment and other structures. It takes place at 40 mph and sends the car into a rigid barrier, with ratings determined by factors like occupant compartment intrusion and the dummy's movement during the crash.

"The numbers confirm that strong performance in the Institute's small overlap front crash test translates into big reductions in fatality risk," said Eric Tech, director of statistical services at IIHS and one of the study's authors.

Interestingly, the older moderate overlap test that involves 40% of the vehicle width returned mostly Good results from vehicles at the time of the small overlap test's introduction. We had a look at some IIHS crash results and found that the small overlap driver-side test is indeed tougher on many vehicles.


The 2022 Jeep Wrangler, for instance, earned a Good rating for the moderate overlap front test but a Marginal rating for the small overlap driver-side test. The 2022 Ford Mustang managed Good and Acceptable scores for the same tests, respectively, again underlining the greater vulnerability of cars in the second scenario.

The IIHS further said that an Acceptable rating was associated with an 11% reduced risk of death for the driver and a Marginal rating a reduced risk of 5%, compared with a Poor rating.

We'd be very interested to see similar real-world studies being conducted for the agency's other front and roof strength tests, along with the stricter side tests that have foiled many small cars. But based on these latest findings, high crash-safety scores are more than just nice-to-haves in your new car - they can actually save your life.


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