IIHS Proves That Its Vehicle Safety Ratings Matter in Real-World Crash Scenarios

The results showed that while driving a vehicle that received a good rating in the driver-side small overlap front crash test, there’s a lower chance of dying in a real-world crash. Specifically, the driver is 12% less likely to be killed in a good-rated vehicle compared to a poor-rated one.

You’re probably wondering what this type of test involves. The driver-side and the passenger-side small overlap test replicates what happens when the front corner of a vehicle crashes with another car or with an object, such as a tree or utility pole. This type of crash is especially dangerous because often, the vehicle’s frame rail isn’t directly hit, so the occupant compartment and other structures must absorb the energy of the impact.

There are two types of overlap tests: moderate and small. The difference is that the former involves 40% of the vehicle’s width, while in the latter, just 25% of the vehicle collides with the barrier. Furthermore, a dummy representing an average-size man sits in the driver’s seat, and the car is traveling at 40 mph (64 kph) toward a rigid barrier.

Several factors are decisive for the final rating. It’s based on the amount of intrusion into the occupant compartment, injury-predicting measurements collected from the dummy, as well as the engineer’s evaluation of how well the restraints controlled the dummy’s movement in the crash.

In 2012, IIHS added the driver-side small overlap front crash to its range of crash evaluations. The issue was that fatal crashes still occurred even though vehicles earned good ratings in the long-running moderate overlap test. Back then, an IIHS demonstrated that small overlap crashes in vehicles with moderate overlap ratings accounted for about a quarter of fatal frontal crashes or impacts resulting in serious injuries.

Eric Teoh, the director of statistical services at IIHS, said that the institution examined only the driver-side test in the study because there’s always a driver when a crash occurs, but the passenger seat is often empty.

At the debut of the small overlap program, with the driver-side test, only about 10% of vehicles tested by IIHS earned a good rating, while 40% were rated 'poor.' Nowadays, every vehicle has a good rating in both the driver and passenger side tests.

To determine how this change was reflected in the rear world, researchers used VIN-decoding software maintained by the IIHS-affiliated Highway Loss Data Institute to pinpoint the make, series, and model year of vehicles involved in frontal crashes between 2012 and 2020. Then, they cross-referenced that data with IIHS driver-side small overlap front crash ratings.

Afterward, researchers calculated the number of driver deaths per police-reported frontal crashes for each rating, then adjusted the results for driver demographics, curb weight, and vehicle type. And that’s how they reached the result I mentioned above.