The writers of "Freakonomics" say people can learn a lot about car crashes from NASCAR.
"NASCAR, in some ways, seem to be much safer than driving on U.S. highways," said "Freakonomics" author Stephen Dubner.
NASCAR has made safety a top priority ever since the sport's biggest star, Dale Earnhardt, died in a high-speed crash on Daytona's last lap five years ago.
The track walls have been cushioned, absorbing some of the shock, and the drivers' seats are safer.
"These seats are strong. They don't move around," said Robin Pemberton, NASCAR's vice president of competition. "You can see the head's surrounded when they take an impact. It's got a couple of inches of foam."
The changes have not reduced the number of accidents. In fact, there are more now than there were five years ago. But in 3,000 crashes in that time span, the number of injuries has fallen and no one has died in competition.
On U.S. highways, there are an average of five deaths per every 1,000 crashes.
"We all have a lot to learn, honestly, from NASCAR," Dubner said.
NASCAR drivers say it starts with building cars and safety equipment that can withstand crashes so the drivers can concentrate on speed, not safety, during competition.
"We're going 200 mph," NASCAR driver Jeff Burton said. "We're not thinking about being safe or we wouldn't be going 200 miles an hour."