The oil shocks of the 1970s forced the American car makers and drivers to use lighter cars in order to reduce fuel consumption. In the 1970s, American vehicles lost 1,000 pounds, while trucks lost 500 pounds. Although these adjustments saved drivers money at the pump, they also resulted in increased road fatalities. According to a 1989 article issued by academics from the Brookings Institution and the Harvard School of Public Health, the change to smaller, lighter cars in the 1970s and 1980s increased mortality by 14-27%. A 2002 assessment by America’s National Research Council concluded that shrinking America’s fleet resulted in thousands of unnecessary fatalities.
But the large cars came back. Between 1990 and 2005, the market share of SUV in America increased from 6% to 26%, raising the weight of the average new car from 3,400lb to over 4,100lb. Larger cars were considered to be safer and families shifted to it.
However, researchers rapidly discovered that the additional protection afforded by heavier vehicles is at the expense of others. Michelle White of the University of California calculated in a 2004 research that for every fatal crash avoided by an SUV, an additional 4.3 deaths occurred among other drivers, pedestrians, and cyclists. Another 2012 report by Shanjun Li of Resources for the Future, a think tank, calculated that when a car collides with an SUV or pickup rather than another car, the driver’s death risk rises by 31 percent. In 2014, Michael Anderson and Maximilian Auffhammer of the University of California, Berkeley found that when two cars collide, a 1,000-pound increase in the weight of one vehicle increased the death rate of the other by 47%.
Researchers also discovered that the safety benefits of vehicle weight had diminishing returns. This indicates that once a vehicle reaches a particular weight, adding more pounds offers little more safety while causing more harm to others. In 2004, Brian O’Neill and Sergey Kyrychenko of the IIHS stated that large cars can end up costing more lives than they save. This makes natural sense, according to Mr Anderson of Berkeley. “When you’re twice as heavy as the other person, will adding 200 pounds make a difference? Probably not for you. But it will ensure that the other side is fully ruined.
The Economist magazine conducted a data analysis of million accidents in the US between 2013 to 2023. The heaviest 1% of vehicles in our dataset—those weighing roughly 6,800lb—suffer 4.1 “own-car deaths” per 10,000 crashes, on average, compared to around 6.6 for automobiles in the center of our sample weighing 3,500lb, and 15.8 for the smallest 1% of vehicles weighing only 2,300lb. However, heavier cars pose a significant risk to other drivers. The heaviest vehicles in our data caused 37 “partner-car deaths” per 10,000 crashes on average, compared to 5.7 for median-weight automobiles and 2.6 for the lightest cars.
To more precisely assess this association, they ran a regression analysis on our 7.5 million two-vehicle crash data. Even after controlling for the curb weight of one’s own car, the age and gender of the driver, the population density of the crash location, and whether the passengers were wearing seatbelts, they discovered that getting into a crash with a 1,000-pound-heavier vehicle is associated with a 0.06-percentage-point increase in the likelihood of dying. Given that the typical fatality rate in a two-vehicle incident is 0.09%, this means that being struck by an additional 1,000 pounds of steel and aluminum—roughly the difference between a Toyota Camry and a Ford Explorer—increases the likelihood of death by 66%.
Source: Economist
