Google Inc. threw the auto industry another curve ball Wednesday, saying its autonomous cars should be on public roads within five years without having to drive through a thicket of regulatory red tape.

Speaking at a conference in Detroit, the chief of the software giant's autonomous-car project, Chris Urmson, indicated widespread auto industry concern about regulation of self-driving cars is overblown. The onus, he said, is on developers of these vehicles to tackle safety challenges and work to boost public acceptance.

"We don't think there is a regulatory block," Mr. Urmson said. Google is working with U.S. regulators on testing driverless cars and "the worst thing possibly we could do is surprise them."

Google shed a spotlight on self-driving cars in 2009, when it began testing its own autonomous cars. The autonomous-car project is part of Google X, the innovations labs behind new and novel technology like Google Glass Web-connected eyewear.

Several auto makers, including Tesla Inc. and Daimler AG, have pointed to concerns about how regulators will view self-driving cars as one of the chief hurdles they face. On Tuesday, for instance, Tesla CEO Elon Musk told the same conference that a lack of clarity on the part of regulators could delay fully-autonomous vehicle introduction until at least 2022.

"We believe there are places in the U.S. where this is legal," Mr. Urmson said, declining to elaborate further, such as how the cars are licensed.

The National Highway Traffic Safety Administration hasn't set firm rules on this segment of vehicles, although most car companies have them under development.

"Just like any car built for use on U.S. roads, any autonomous vehicle would need to meet applicable federal motor vehicle safety standards, which falls under NHTSA's jurisdiction," an agency spokesman said. "The agency will have the appropriate policies and regulations in place to ensure the safety of these types of vehicles."

In addition to safety and public acceptance, Mr. Urmson said the expense of such vehicles is also an obstacle. The cluster of radars and lasers that sits above the car costs about $75,000 today, but that cost is likely to come down with higher production volumes.

Google has been knocking on doors among the more established auto industry players to find help making a driverless car on a larger scale. General Motors Co. and Fiat Chrysler Automobiles are among the auto makers who say they have discussed the topic with Google.

"We're definitely not in the business of making cars," said Mr. Urmson, who says he typically rides his bicycle to work.

Google also has forged partnerships with auto suppliers like Continental AG and Robert Bosch GmbH to engineer prototypes. No matter how much work on sensors and other components the partners do, the cars won't be completely crash proof, Mr. Urmson said.

"There will be failures of these vehicles," he said. "We need to get to the point where we accept that."

Mr. Urmson said Google isn't interested in developing semiautonomous features. Rather, it wants to fully automate driving. Mr. Urmson said Google's safety threshold is being developed internally. "We still have work to do," he said.

Write to Christina Rogers at christina.rogers@wsj.com

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