For years, automakers and overprotective dads agreed on one thing: bigger, heavier vehicles are safer in a crash. The logic? A heavy SUV or truck plows through smaller cars, keeping its own occupants safe. The Insurance Institute for Highway Safety (IIHS) once supported this idea. But new research flips the script—but not before a “bigger is safer” arms race led to countless preventable deaths.

The hidden dangers of heavy vehicle crashes

Heavy vehicles do plow through lighter ones, right? That’s exactly the problem. They kill more people in smaller cars, cause more collateral damage, and are especially deadly to pedestrians. Worse, IIHS data now suggests they may not even protect their own occupants as well as once thought.

IIHS previously stated, “A bigger, heavier vehicle provides better crash protection than a smaller, lighter one.” But even that study warned, “Large vehicles are more dangerous to pedestrians and bicyclists.” Now, the latest research challenges the “bigger is better” myth entirely.

IIHS reverses its stance on heavy vehicle crashes

IIHS analyzed 440,604 driver fatalities between 2011 and 2022, focusing on newer (1- to 4-year-old) vehicles. It found that while extremely lightweight cars are indeed more dangerous to occupants. But protection plateaus at 4,000 pounds. Anything heavier offers no extra safety for the driver or occupants. Instead, added weight just increases the likelihood of killing someone else.

The study states, “For heavier vehicles, additional weight provided negligible extra protection but a substantial increase in crash partner risk.” In other words, a heavy vehicle crash doesn’t only fail to offer additional protection for its driver—it’s far more likely to be fatal for the other guy.

Pedestrian deaths: the overlooked crisis

Not only do heavy vehicles make crashes deadlier for other drivers, they’re also a nightmare for pedestrians. Modern SUVs, pickups, and vans have hoods over 40 inches tall. The IIHS found they are “45% more likely to cause fatalities than shorter vehicles.”

David Harkey, IIHS president, explained why: “The vehicle is striking the pedestrian much higher in the torso region and tends to push the pedestrian forward and down.” This leads to severe injuries, especially head trauma. These vehicles also have huge blindspots, making it very difficult to spot children.

We have seen a marked increase in pedestrian deaths and serious injuries in recent years. The result of a collision like this could be trauma, guilt, and even an expensive lawsuit.

How heavy a vehicle is safest in a crash?

IIHS found that vehicles get safer for their own occupants—up to 4,000 pounds. Heavier than that? The benefit disappears. So what actually fits in the sweet spot? Not an F-150. Not even a Toyota 4Runner, which weighs closer to 5,000 pounds.

Surprisingly, a BMW 5 Series or an old Dodge Charger sedan hovers right around 4,000 pounds. Neither of these scream “tank-like safety,” but the numbers don’t lie. The safest vehicle in a heavy vehicle crash isn’t the biggest one—it’s the one engineered to absorb impact without crushing everything in its path.

Want to survive a crash? Maybe skip the three-ton SUV. And if you care about other people surviving too, definitely give it a pass.