According to a new study from transportation researchers, self-driving cars are more prone to get into accidents than cars driven by humans. Google, Delphi, and Audi's self-driving vehicles accident records from 2012 through September 2015 were analysed by Brandon Schoettle and Michael Sivak of the University of Michigan's Transportation Research Institute.
The findings had an average crash rate of 9.1 per million miles travelled, versus 4.1 for conventional vehicles. The study also highlighted, Google's fleet of self-driving cars was involved in 11 crashes. Most of the vehicles involved in accidents were hit in the rear while travelling at 5 miles per hour or slower.
The authors noted the 11 crashes involving Google cars were not the self-driving vehicles fault, and there were no fatalities or injuries. The study also notes that self-driving cars haven't been around for long and had only recorded 1.2 million miles (the majority by Google cars) compared to 3 trillion annual miles in the U.S. by conventional vehicles.
Google was quick to caution against drawing conclusions from the report.
"In more than 1.2 million miles of autonomous driving since the start of our project in 2009, not once has our self-driving car been the cause of a collision. We publish the details of all crashes we've been involved in on our website each month, and there's a clear theme of human error and inattention," the company said in a statement to NBC News. "The researchers themselves concede in their report that the actual crash rates of for self-driving vehicles could be lower than for conventional vehicles."