David Leonhardt on driving deaths in the US in The New York Times:
Had the United States kept pace with the rest of the world, about 10,000 fewer Americans each year — or almost 30 every day — would be killed. Instead, more people die in crashes than from gun violence. Many of the victims, like Erin Kaplan, were young and healthy.
“The overwhelming factor is speed,” says Leonard Evans, an automotive researcher. Small differences in speed cause large differences in harm. Other countries tend to have lower speed limits (despite the famous German autobahn) and more speed cameras. Install enough cameras, and speeding really will decline.
See also: this Numberphile video (via Kottke), which proves that “going from 70 mph to 100 mph more than doubles your energy…and going from 55 to 100 more than triples it.”