Chris Urmson, head of Google's self-driving car program, has talked at length about the challenges autonomous-drive vehicles face by sharing the road with conventional cars and trucks.
While computers in the Google prototype can steer through traffic based on what's happening in front of them or in the lanes on either side, they are unable to avoid being rear-ended by a car approaching at a stop sign or intersection.
In September, Urmson declined to predict when self-driving cars would be out on roads in larger numbers.
"We don't really have a set timeline because first and foremost this is really about safety, and we don't want to rush that," he said at the time. "It has been amazing to see how the technology has developed over the last few years."
Delphi spokeswoman Amy Messano said that although the company has not yet seen the results of UMTRI's study, "Delphi's self-driving prototype has not been involved in any accidents while testing its autonomous-drive technology."
Google says its self-driving cars have caused exactly zero collisions in the 1.2 million miles of autonomous driving they've done since the project started in 2009.
"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," a Google spokesman told CNBC. "The researchers themselves concede in their report that the actual crash rates of for self-driving vehicles could be lower than for conventional vehicles."
Audi did not immediately respond to a request for comment.
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