WASHINGTON – Auto industry officials and researchers told Congress this month technology that could lead to self-driving cars is gradually improving, but these vehicles will not be on the market in the immediate future.

Driverless cars, also referred to as autonomous cars, have sparked the public’s imagination and countless news stories. Interest in them spiked last year, when Google announced it would make the technology available to the public within five years. Since 2010, the tech giant has logged hundreds of thousands of accident-free miles in driverless vehicles.

A certain degree of automation is already available to consumers in many new car models – such as automatic parallel parking and adaptive cruise control – and the integration of those technologies with throttle and steering control could reduce the need of driver control of the vehicle. Autonomous cars will be capable of navigating roads with limited or no action from the driver by utilizing a variety of optical sensors, radar, and computer algorithms.

Lawmakers convened a panel to examine the technology and the technical advances that have led many to believe that autonomous cars could be on the road by the end of the decade.

Mike Robinson, General Motors’ vice president of sustainability and global regulatory affairs, told the House Highways and Transit Subcommittee that for the foreseeable future drivers will “still need to be engaged and in control.”

“These types of driverless systems are a significant distance into the future,” Robinson said. “This is because driving is very complicated business and it will take some time for the computer-driven systems to be capable of managing and reacting to all of the situations and road conditions that drivers do encounter.”

Raj Rajkumar, who heads the Carnegie Mellon University driverless car research project, said further research is required to address the challenges presented by such ordinary events as bad weather, poor road conditions, and different lighting conditions.

His team won a competition for autonomous vehicles in 2007, funded by the Defense Advanced Research Projects Agency (DARPA).

Rajkumar said his team is looking at ways to improve “connected vehicle technologies” that would allow cars to communicate with each other, and with pedestrians and other vehicles on the road, via wireless radio.

Andy Christensen, senior manager of technology planning at Nissan, noted the company’s CEO has vowed to have an autonomous vehicle ready to sell by 2020.

“This timeframe is challenging, but we believe achievable,” he said.

National Highway and Traffic Safety Administration (NHTSA) chief David L. Strickland said autonomous vehicles could help save thousands of dollars in economic costs to society from car crashes and, more importantly, reduce the number of lives lost in fatal accidents.

Earlier this year, NHTSA issued plans for research on autonomous vehicles, including proposals to look into connected vehicle technology.

Strickland told lawmakers that his agency was following closely the development of self-driving cars. “Automated driving is an exciting frontier for the industry, and we have identified three key areas for preliminary research: human factors and human-machine interface, initial system performance requirements, and electronic control system safety,” Strickland said.

Four states have passed laws permitting autonomous cars: Nevada, California, Michigan, and California. Last week, Michigan voted to allow testing of these vehicles on the state’s roads. Similar bills are before lawmakers in New Jersey, Oklahoma, Hawaii, and the District of Columbia.