Google is known for setting ambitious targets for itself, and it's apparently making no exception for self-driving cars. Such "autonomous vehicles" will be a reality for "ordinary people" in less than five years, Google co-founder Sergey Brin said Tuesday.

He also said autonomous cars will be "far safer" than those driven by humans, and he envisioned a world in which office parking lots become a thing of the past, with cars instead dropping off their owners and driving off to park themselves somewhere else.

Brin, also Google's director of special projects, spoke at a press conference at Google's Silicon Valley headquarters, where California Gov. Jerry Brown signed into law state legislation that is designed to accelerate the testing and development of self-driving vehicles. Watch an IDG video report on the news here.

SB 1298, authored by State Sen. Alex Padilla, creates a legal framework and safety standards for the testing and operation of autonomous cars.

The bill requires, among other things, that a driver be present to take control of the vehicle when needed. It also says autonomous vehicles can only be used for testing until the state has granted various safety approvals. It follows similar legislation passed in Nevada.

"We're stepping on the accelerator when it comes to the Google car," Padilla said at the event.

Brin was asked how long he thinks it will be before self-driving cars are a reality for everyday people. Google engineers are already testing the cars and the company hopes to let more employees start testing them within a year, he said.

"And I would hope people can more broadly utilize this technology within several years after that," Brin said.

He added quickly that he was reluctant to "overpromise" and said Google has set ambitious targets for its engineers. "You can see them stressing, looking at me answer this question," he joked, indicating some Google engineers in the audience.

Then he said: "You can count on one hand the number of years until ordinary people can experience this."

The Google cars use on-board cameras, lasers, radar and other sensor equipment to monitor road conditions and operate themselves. Proponents say the use of computers and other equipment will make them safer than having humans drive, since people sometimes make errors, lose concentration, fall asleep or drive drunk.

Forty thousand Americans and 1 million people worldwide are killed in automobile accidents every year, Brin said.

"I expect self-driving cars are going to be far safer than human-driven cars," he said.

Still, autonomous vehicles will face a lot of scrutiny before they are allowed on the road, and there's still a lot of work to be done, he said.

Google's cars have done about 300,000 miles of road testing, but not without incident, Brin said. The most the cars have achieved without "safety-critical intervention" -- or a driver needing to take control -- is about 50,000 miles, he said.

"That's not good enough, and we're continuing to work to go beyond that," he said.

"Safety is a huge challenge for us. That's one of the most difficult things that we undertake from a technology point of view, because there are never enough 'nines' in terms of getting things right," Brin said, using a reliability term from the computer industry.

"What happens when a computer breaks down, or when the tire blows out or something unexpected happens? We spend night and day fretting about all sorts of rare possibilities, and I'm optimistic that we're going to be able to solve [these issues]," he said.

Vehicle safety isn't the only thing on people's minds, however. Consumer Watchdog, a nonprofit group, tried to get the California bill blocked unless it included language that prevented companies from collecting data for marketing or any other non-safety purposes.

Brin thinks the benefits will outweigh other concerns. Self-driving cars will be more fuel-efficient, lead to less accidents, and open doors to blind people and others who are "under-served by the current transportation system," he said.

"Some people have disabilities, others are too young, some people are too old, sometimes we're too intoxicated," Brin said.

Self-driving cars will also relieve congestion, according to Brin, because they will be able to drive closer together on highways

But toward the end of the press conference, he came back to how much work remains to be done.

"It's dealing with every possible eventuality," he said, "and we're dealing with a long list of eventualities."

But humans have overcome those challenges before, he said. "For instance, for airplane flight."

Google Co-Founder Sergey Brin wore Google glasses during the event, where Gov. Jerry Brown signed the law allowing self-driving cars. The bill, SB1298. also establishes rules, like a driver must be in the car the entire time.

James Niccolai covers data centers and general technology news for IDG News Service. Follow James on Twitter at @jniccolai. James's e-mail address is james_niccolai@idg.com