As electric vehicles become more common, concerns over their safety, not just for those who drive them but for others on the road as well, are also increasing.
Tests performed by the Insurance Institute for Highway Safety (IIHS) show EVs hold up well in a simulated crash. Their batteries make the vehicles heavier, offering better protection to the passengers inside, but that extra weight — hundreds to even thousands of pounds — has traffic safety advocates concerned about the potential risk to other drivers.
"I think it does present significant challenges for safety," National Transportation Safety Board chair Jennifer Homendy told CBS News. "If you think about an impact in a crash with a lighter vehicle with a pedestrian or a cyclist or motorcyclists, it's going to have a much different outcome than we've seen in the past. Terribly tragic."
When asked if she was concerned it could lead to more deaths on the road, Homendy answered, "Absolutely it could. There's not a focus on the safety aspect of this."
The average vehicle on the roads as of mid-2023 weighed around 4,300 pounds, according to government data, but some newer large EVs weigh thousands of pounds more. That difference, crash experts say, matters.
"It's simple laws of physics," said Raul Arbelaez, vice president of IIHS' Vehicle Research Center in Ruckersville, Virginia. "The crash for the other vehicle, when you are heavier, is going to be more severe."
GMC's Hummer EV weighs more than 9,000 pounds and can go from zero to 60 in roughly three seconds. It is more than 3,000 pounds heavier than the GMC's full-size pickup. The Hummer EV's battery alone weighs about the same as a Toyota Corolla sedan.
The electric Ford F-150 Lightning pickup is up to 2,500 pounds heavier than the lightest gas-powered version of the vehicle model. Rivian's R1 pickup weighs around 7,100 pounds.
IIHS testing found that a significant weight difference between vehicles can have a noticeable impact in a crash. In a March 2018 test, a 2018 Kia Forte sedan and a 2016 Kia Sorento SUV, weighing 928 pounds more than the sedan, were crashed into each other at 40 miles per hour, simulating a near head-on collision. IIHS found the forces on the driver dummy in the sedan were much greater than those in the SUV.
Post-crash analysis found a high likelihood of head injuries for the driver of the Forte, likely injuries to the leg and possible injuries to the neck and chest. In contrast, the Sorento SUV test dummy had mostly good injury measurements, aside from a possible right leg injury. The sedan also suffered visibly more damage than the SUV.
"In short, the 2018 Forte was a good performer in crash tests and stood out as a very safe choice among small cars," IIHS spokesman Joseph Young told CBS News. "However, the extra weight of the Sorento pushed the limits of what the smaller car could handle, leading to additional structural intrusion and higher risk of injury, even with the two vehicles traveling at the same speed."
According to a 2011 study published by the National Bureau of Economic Research, a 1,000-pound difference between vehicles results in a 47% increase in the likelihood that a crash turns deadly.
"A 7,000-pound vehicle hitting a 4,000-pound SUV, the impact on that smaller vehicle is going to be quite significant," said Arbelaez. "It is going to be a more severe crash with more intrusion and higher levels of injury."
Arbelaez has previously written about his concerns that heavier EVs on the roads could pose a safety risk for other drivers.
"You take a very large vehicle, say a 10,000-pound vehicle, against that mid-size SUV. You have now converted that from a 40 mph crash for that smaller vehicle all the way to about a 58 mph crash," Arbelaez explained. "And what crash research tells us is that once you go above, say, the standard 40 mph crash severity, to 55 [mph] and higher, safety for those occupants in those vehicles goes down dramatically. The occupant compartment starts to collapse in ways that we aren't designing for."
Traffic safety advocates acknowledge that vehicle weight is just one factor in a crash. In addition, while EV sales are surging, they remain a small fraction of the total number of vehicles on the roads, making crash and injury data limited.
The nation's top road safety regulator, the National Highway Traffic Safety Administration (NHTSA), said it is closely monitoring this topic and is conducting "extensive research" on the differences between gas-powered vehicles and EVs. An agency spokesperson told CBS News that research includes investigating size- and weight-related crash implications.
As of 2023, NHTSA said it was not aware of any differences in crash outcomes between electric and non-electric vehicles.
NHTSA was unable to provide any specific crash data involving those EVs when requested by CBS News. It's worth noting the heavier electric SUVs and trucks have only been on the roads in relatively large numbers for about a year.
"I think it's great that we are focused on air quality, but we are not focused on safety with these vehicles. The two are not mutually exclusive. We should aim for improved safety and improved air quality," Homendy said.
The Alliance for Automotive Innovation, a trade association representing automakers, wrote in a statement to CBS News, "Safety is a top priority of the auto industry. Vehicles on the road continue to get even more safe as automakers across the board test, develop and integrate breakthrough safety technologies like automatic emergency braking that help save lives and prevent injuries."
That automatic emergency braking is already commonplace in EVs and many new gas-powered vehicles. NHTSA announced in May that it will require AEB on all new passenger cars and light trucks, which the agency expects will dramatically reduce rear-end and pedestrian crashes.
Automakers have been adding AEB technology on a voluntary basis since a 2016 agreement to equip at least 95% of passenger cars and trucks with the technology. IIHS expects the voluntary commitment alone to prevent 42,000 crashes and 20,000 injuries by 2025.
On its test track, IIHS demonstrated one such collision avoidance system installed in a nearly 5,000-pound electric SUV. It successfully stopped the vehicle traveling at about 20 mph before it hit a car-shaped obstacle and another resembling a pedestrian.
Kris Van Cleave is CBS News' senior transportation and national correspondent based in Phoenix.
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