Self-driving cars are no longer science fiction. With seven companies testing automated vehicles on California highways, many in the Bay Area, and others working in labs and on test tracks, the promise of leaving at least some of the driving to your car is becoming a reality.

On Sunday, one automated car developer will demonstrate the momentum behind the driverless car by taking one on a 3,500-mile road trip that will start near the Golden Gate Bridge and travel across the country to the New York International Auto Show.

Much as Detroit became Motor City, Northern California is becoming the center of driverless car development. Much of the American research into self-driving cars is taking place in or near Silicon Valley, and Sacramento is leading the way in regulating the vehicles.

Despite the progress and interest in self-driving cars, visions of a carefree commute — sipping on cocktails while the car heads home across the Bay Bridge at sunset or reading the newspaper over your coffee while the car carries you to work — may have to wait.

So, too, will traffic relief. Some researchers believe that self-driving cars may cause more congestion, not less — at least until a lot of them are on the road.

Depending on how you define “self-driving” and whom you believe, automated cars are either just around the corner or still a couple of decades from reality. At least the cocktails and coffee version.

Some automated transportation researchers and developers — they call the field “intelligent transportation” — believe the public has developed an unrealistic view of automated cars, driven perhaps by wishful thinking, the Internet and even some of the science fiction visions from the past.

Countering hype

Hossam Bahlool, director of automotive products for Telenav, which produces navigation products and is working on self-driving technology, describes the public perception as “Hollywoodesque,” though he acknowledges it would be enjoyable to sit back and sip an after-work drink on the drive home.

“My concern is that the public’s expectations have been raised to unreasonable levels because of the hype out there on the Internet,” said Steven Shladover, a research engineer with a UC Berkeley advanced transportation program. “It is our job to rein that in a bit. ... I’m sometimes the skunk at the picnic when I say it’s probably not going to happen anytime soon.”

Automotive automation is already on the market and is becoming increasingly common. Adaptive cruise control not only applies the gas but also the brakes and maintains a steady speed at a safe following distance from the car ahead. Parking assist features will pull the car into a parking space for you with a steadiness even a Department of Motor Vehicles examiner would admire.

The National Highway Traffic Safety Administration, and most automated car developers, use a five-stage progression to both describe and envision the advance of self-controlled cars. Level zero is a car completely controlled by the driver. Level one involves automation of a single function like electronic stability control braking. Level two combines two or more functions such as adaptive cruise control combined with technology that keeps a car in its lane. Cars offering those features are already on the road.

Increased automation

The third level allows drivers to relinquish control of the vehicle under certain conditions — on freeways, for instance, or at certain speeds — but they must remain behind the wheel and be ready to take over operations, with the car allowing some time to make the transition. Such cars are being tested but are not yet on the market.

Level four is a fully automated car that requires nothing of the driver but to designate the destination, sit back and enjoy the ride. This level could be used with or without passengers in the car, allowing drivers to push a button and send the car home on its own.

John Absmeier, who runs the autonomous cars division of Delphi, an automotive technology firm, figures Level three cars could be on the road by 2017 or 2018 but that fully self-driving cars are unlikely for at least 10 years.

“Automated chauffeurs — we see that as kind of far out,” he said.

Google’s goal

Shladover expects fully automated cars to be operating on freeways and possibly on some city streets in the 2020 to 2025 range but not in dense urban areas like downtown San Francisco before the 2030s. It could take another 20 years before blind or disabled people are able to hop in a car and have it take them to their destination.

Not everyone is so conservative. Google, which has become widely associated with self-driving car research, is no longer following the incremental approach of developing automated features that assist drivers. Instead, it’s working solely on a driverless car that can take anyone door to door.

Toward that goal, the Mountain View company abandoned the idea of testing its cars on freeways about a year and a half ago and is working instead on perfecting its technology on city streets, which is considered much more challenging.

Still, Google officials have made public statements, including to Gov. Jerry Brown, indicating that they think they can have a fully self-driven car in about five years. Google representatives would not comment on details of their program.

When self-driving cars do hit the road, drivers shouldn’t expect an immediate improvement in traffic. In fact, Shladover says, self-driving cars are likely to cause more congestion until there are enough cars on the highways that talk to one another.

Slower reaction time

Such cars use technology that enables them to detect the car in front of them, maintain a safe following distance, or brake to a stop. But unlike human drivers, he said, that technology is unable to see three or four cars ahead and begin braking or changing lanes. The slower reaction time has a ripple effect. In an experiment using four self-driving cars that followed each other, the rear car was slowed so much, Shladover said, that a frustrated driver would have liked to switch off the automation.

Self-driving cars won’t be fully efficient until they’re able to talk to each other and as many other vehicles as possible, Shladover said. Federal safety officials want to require all new cars to be equipped with what’s known as vehicle-to-vehicle communication — a system that broadcasts their speeds and positions 10 times per second.

In addition to the technological challenges, self-driving cars also have to overcome the obstacles of regulation, public perception and cost. Northern California has become the center of self-driving car development in North America. Most of the driverless car research takes place in the Bay Area, and the state DMV is charged with regulating both testing and eventual public use of automated cars.

DMV’s concerns

Companies wanting to test self-driving cars on public roads and highways need to get a permit from the DMV and satisfy state requirements that include using only drivers with clean records and proper training, having a driver ready to take control at all times, and having at least $5 million in cash or insurance available to cover claims.

Regulations for testing were in place at the beginning of the year, as required by state legislation, but the rules for the public are still in development, said Bernard Soriano, the DMV’s deputy director. Some self-driving car developers have complained that the DMV’s deliberative approach has become a hindrance.

Among the things to be determined are whether a driver or operator would need to be ready to intervene, whether steering, acceleration and braking controls should be required, and what changes in the state vehicle code will be necessary.

“It’s peppered with what the driver can and cannot do while driving,” said Soriano, who offered no prediction of when regulations are likely to be ready.

Contra Costa County officials are working with Mercedes and other automotive developers to turn part of the former Concord Naval Weapons Station into a testing center — called GoMentum Station — for vehicle-to-vehicle communication and self-driving cars. The station has roads, tunnels, bridges, rail crossings and a small area that was once a town.

“We’re trying to push this technology forward,” said Randy Iwasaki, executive director of the Contra Costa Transportation Authority and a former Caltrans director. “We’re an hour from Sacramento, where the regulations are being created, and 38 miles from Silicon Valley.”

Overcoming resistance

Public perception will also be an important factor in accepting the cars. Poll results vary but seem to show the public warming to the idea of self-driving cars, though there are concerns about safety and how the vehicles would share the roads with standard motor vehicles.

“A lot of people are naysayers about the technology and are unwilling to give control over to the car,” Bahlool said. “But once you try it, you’re sold.”

In its cross-country trek, Delphi hopes not only to generate interest in self-driving cars but advance its research by testing a driverless vehicle on a long trip under varying traffic, weather and road conditions. It is believed to be the longest test-drive of an automated car in North America. While the automated systems are expected to do most of the driving, a trained driver will be behind wheel of the specially outfitted Audi Q5, and ready to take over, at all times.

Costs to decline

Cost will also be a factor, of course. The average new car purchase is in the $20,000 range, but the high-tech gear required on self-driving cars being tested adds tens of thousands of dollars. Google’s driverless car is said to include at least $150,000 of technology. Costs will fall after research and testing turn to mass production, however, and some experts project the additional cost of a self-driving car at about $10,000.

While the self-driving car may remove much of the stress from the commute, what are the chances it will be transformed into a moving happy-hour cocktail lounge?

“It’s pretty unlikely drinking and driving is going to be allowed,” Absmeier said. “But that’s up to the state.”

Michael Cabanatuan is a San Francisco Chronicle staff writer. E-mail: mcabanatuan@sfchronicle.com Twitter: @ctuan