Self-driving cars may not be proven safe for decades: report

U.S. Transportation Secretary Anthony Foxx and Google executive chairman Eric Schmidt listen to Chris Urmson, director of Google's self-driving car project, discuss the revolutionary vehicle at the Google campus in Mountain View, Calif., in February 2015. (Karl Mondon/Bay Area News Group/TNS)

Google's self-driving cars may have driven themselves 1.5 million miles since 2009, but it could take hundreds of years for robot-car makers to prove safety at the current testing rate, a new study said. 

"Given that current traffic fatalities and injuries are rare events compared with vehicle miles traveled, we show that fully autonomous vehicles would have to be driven hundreds of millions of miles and sometimes hundreds of billions of miles to demonstrate their safety in terms of fatalities and injuries," said the Driving to Safety report from the Rand Corporation.