We are all aware that all-electric vehicles are heavier than internal combustion vehicles because of the weight of their batteries. Many of the current generation of EVs exceed 6,000 pounds, with the GMC Hummer EV weighing around 9,500 pounds.

When two vehicles collide, the heavier vehicle pushes the lighter one backward, resulting in higher forces on the people in the lighter vehicle and lower forces on people in the heavier vehicle. That’s why the Insurance Institute for Highway Safety (IIHS) stipulates that their frontal crash test ratings — which are conducted against a fixed barrier and simulate a crash with an identically sized vehicle — can only be compared among vehicles of similar weight.

Assuming the new generation of heavy EVs is designed to perform well in the IIHS crash tests, there is no reason they can’t provide good protection to their occupants. In fact, their extra weight will afford them greater protection in a multivehicle crash. Unfortunately, given the way these vehicles are currently designed, this increased protection comes at the expense of people in other vehicles, according to Raul Arbelaez, vice president of the Vehicle Research Center in Ruckersville, Virginia.

Incidentally, I had the pleasure of a tour of this facility several years ago, when my daughter and family lived in Charlottesville, Virginia. Unfortunately for me, the day I visited the research center, they weren’t test-crashing any vehicles.

Over the years, the IIHS has conducted several demonstration crashes that paired larger vehicles with smaller ones to show the effect of size and weight on crashes. In two 2018 tests, one involving a midsize SUV and a small car and another involving a large car and a minicar, both smaller vehicles performed poorly.

The extra weight of EVs may also present a threat to pedestrians and bicyclists, though the danger for them is not as straightforward. The weight differential between a person and any type of passenger vehicle is already so enormous that the additional weight from an EV battery would make little difference in most cases. However, it’s not clear that all EVs have braking performance that matches their additional mass. If the extra weight leads to longer stopping distances, that will likely lead to an increase in pedestrian and cyclist deaths, which already have been on the rise in recent years.

And while there are questions about braking performance, we already know these vehicles have no problem accelerating. Today’s supersized EVs are a double whammy of weight and horsepower. While there were many heavy vehicles on our roads before EVs, a delivery truck isn’t designed to go from 0 to 60 in around three seconds like the Hummer mentioned earlier or the 7,000-pound Rivian R1T pickup, says Arbelaez.

If the present trend toward ever-heavier, more powerful EVs continues, there will be a big increase in the number of super-heavy, high-acceleration machines all around us, including in residential neighborhoods. That will make a collision involving a huge weight disparity much more likely, according to Arbelaez.

“We don’t need to put the brakes on electrification — there are good reasons for it — and we’re not doomed to reverse all the safety gains of recent decades. But the development will require some new thinking about the kinds of vehicles we want on our roads,” said Arbelaez.