Google, Lyft and auto industry executives urged lawmakers Tuesday to help create a regulatory fast lane to help the deployment of self-driving cars.

In testimony at a Senate hearing, representatives of General Motors and auto-equipment maker Delphi touted numerous safety and environmental benefits of autonomous vehicles.

Chris Urmson, who heads the Google self-driving car project, said a consistent regulatory framework is important to deploying those technologies, and that conflicting rules in US states could limit innovation.

"The leadership of the federal government is critically important given the growing patchwork of state laws and regulations on self-driving cars," he said.

In the past two years, 23 states have introduced legislation that affect self-driving cars, "all of which include different approaches and concepts," he noted.

Five states have passed such legislation, all with different rules, Urmson said.

"If every state is left to go its own way without a unified approach, operating self-driving cars across state boundaries would be an unworkable situation and one that will significantly hinder safety, innovation, interstate commerce, national competitiveness and the eventual deployment of autonomous vehicles," Urmson said in his prepared testimony.

He also cited government statistics showing 38,000 people were killed last year in US road accidents and that "94 percent of those accidents involve human error."

Joseph Okpaku, vice president of government relations for the ridesharing group Lyft, echoed those comments, saying consistent rules would be important for the planned deployment of self-driving cars by Lyft and GM.

"We are on the doorstep of another evolutionary leap in transportation and technology, where concepts that once could only be imagined in science fiction are on the verge of becoming a reality," he said.

"The worst possible scenario for the growth of autonomous vehicles is an inconsistent and conflicting patchwork of local, municipal and county laws that will hamper efforts to bring AV (autonomous vehicle) technology to market," Okpaku added.

"Regulations are necessary, but regulatory restraint and consistency is equally as important if we are going to allow this industry to reach its full potential."

GM vice president Michael Ableson said the auto giant "enthusiastically supports policy initiatives to accelerate the development and adoption of safe, high-level vehicle automation."

Delphi vice president Glen De Vos added that "uniform rules that allow for the safe operation of driverless vehicles in all 50 states will be critical."

- Not so fast -

But the Senate panel was told to exercise caution by Mary Cummings, who heads the Humans and Autonomy Laboratory at Duke University.

Cummings said it's not yet clear that self-driving cars can safely operate in all situations.

"We know that many of the sensors on self-driving cars are not effective in bad weather, we know people will try to hack into these systems," she told the panel.

Cummings said it is possible to "spoof" a car's GPS to send it off course, or to use laser devices to trick a vehicle into sensing objects which are not there.

She said a Rand Corporation study said that self-driving cars would need to drive 275 million miles (442 million kilometers) to show they are as safe as human-operated vehicles.

Cummings said the federal government needs to ensure that testing is done in a rigorous way to ensure safety.

"I am wholeheartedly in support of the research and development of self-driving cars," she said.

"But these systems will not be ready for fielding until we move away from superficial demonstrations to principled, evidenced-based tests and evaluations."

The activist group Consumer Watchdog warned meanwhile that the federal government should not take shortcuts on safety by "rushing new technology to the roads."

"Federal regulators have a process for writing rules to keep the public safe," Consumer Watchdog's John Simpson said in a statement.

"Congress shouldn't skirt those rules just because tech industry giants like Google ask them to."

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GENERAL MOTORS

DELPHI AUTOMOTIVE

GOOGLE