Carmakers are making vehicles more crashworthy about three times faster now than they did in the mid-1990s, but those improvements and new safety features still take decades to filter into most vehicles on the road, according to an analysis by the Highway Loss Data Institute ("HLDI").
"The speed at which manufacturers are improving crashworthiness and rolling out new safety features has increased markedly in recent years," said Matt Moore, senior vice president of HLDI. "But the advancements make their way into the broader fleet at varying rates."
The HLDI analysis looked at four ratings evaluations of the Insurance Institute for Highway Safety ("IIHS"): moderate overlap front, side, roof strength, and driver-side small overlap front.
In the moderate overlap frontal test, which was introduced in 1995, a vehicle traveling at 40 miles per hour crashes into a fixed barrier with 40 percent of its front width. In the side-impact test, which began in 2003, a 3,300-pound projectile shaped like the front of an SUV hits the driver side of the test vehicle at 31 m.p.h. In the roof strength test, introduced in 2009, a metal plate pushes down on the test vehicle's roof until it crushes five inches. And in the driver-side small overlap test begun in 2012, the test vehicle hits a barrier at 40 m.p.h. with 25 percent of its front width.
While the percentage of the tested vehicles that earn a good rating in the oldest test — the moderate overlap — has increased an average of two percentage points per year, the rate of increase has accelerated to six percentage points per year for the newer driver-side small overlap test, HLDI's analysis showed.
"As independent safety ratings gain prominence, they have become an important marketing tool for carmakers, resulting in faster rollouts," Mr. Moore said.
Nevertheless, the HLDI said, it still takes decades for improvements to impact the entire fleet of registered vehicles. That's because drivers do not immediately abandon older vehicles when automakers make safer ones.
Even 23 years after its introduction, the percentage of the U.S. fleet with a good rating in the moderate overlap test is only 64 percent. Six years after the introduction of the driver-side small overlap test, only 14 percent of the fleet earns a good rating in that evaluation.
The HLDI pointed out that a parallel study of the speed at which advanced safety features make their way into the overall U.S. fleet suggests that government mandates and voluntary manufacturer commitments also have a powerful impact on the pace of change.
In this study, researchers looked at the estimated availability and installation of rear cameras, rear parking sensors, blind spot monitoring, forward collision warning, front automatic emergency braking, lane departure warning, and curve-adaptive headlights from the years these features were introduced through calendar year 2050.
The HLDI explained that with the exception of curve-adaptive headlights, these features have been filtering into the broader fleet at a faster rate in recent years than happened earlier. But two features that are required by government mandate or slated for universal adoption by a voluntary manufacturer commitment — rear cameras and front autobrake — are spreading even faster since those measures were announced.
According to the HLDI, even features that are rapidly becoming more common will take a long time to spread through the registered-vehicle fleet. Only rear cameras, which were first introduced in model year 2002 and now are required on all new vehicles, are expected to be installed on more than half of all registered vehicles by 2023.
The percentage of the fleet equipped with front autobrake, which was introduced in model year 2006, is expected to increase nearly fivefold to 24 percent in 2023 from about five percent in 2018.
However, curve-adaptive headlights, which, according to HLDI data, lower claim rates, will grow only one percentage point a year to reach 10 percent by 2023.


