Are heavy trucks a Nash Equilibrium?

Economist: America's love affair with big cars is killing them.

In America the average new car weighs more than 4,400lb (2,000kg) compared with 3,300lb in the European Union and 2,600lb in Japan. In 2023 vehicles weighing more than 5,000lb accounted for a whopping 31% of new cars, up from 22% five years earlier. As a London cyclist I find these numbers staggering—and scary. Our analysis shows that—aside from posing a risk to pedestrians and cyclists such as myself—the inflated weight is becoming a growing risk to the drivers of other, smaller cars. The fatality rate is roughly seven times higher when colliding with a heavy pickup truck than with a compact car.

Conservation of momentum also suggests that if you are driving a heavy pickup truck, your fatality rate is much lower. By analogy to a prisoners' dilemma, it appears that the equilibrium is to drive as heavy a vehicle as likely. 

 BOTTOM LINE: if you drive a heavy truck, I do better by driving a heavy truck, and vice-versa. In other words, we are in a Nash Equilibrium.

UPDATE: Why American Cars are so Big

Today the law mandates 40mpg. To increase efficiency, manufacturers had to use more complex engines, which made their cars costlier. To ease the burden on small businesses that relied on big vehicles, the government exempted “light trucks”, any vehicle that could be used off road and weighed less than 8,500lb (3855kg). That meant SUVs—typically among the biggest and least-efficient cars—were swept into the category and avoided the new fuel standards.

Because making light trucks held to lower environmental standards was more profitable than building small clean cars, automakers marketed big models, including SUVs, enthusiastically. They portrayed them as quintessentially American, embodying freedom, strength and adventurousness. By 2002 light trucks made up a bigger share of light-duty vehicle sales than cars.