Big auto makers are steering their efforts to develop cars that drive themselves out of the labs and into the fast lane for production, after years of low-profile experimentation.

Auto industry executives on Tuesday used the podium offered by the biennial Frankfurt auto show to deliver that message in a variety of ways, responding in part to software giant Google Inc.'s well-publicized experiments with autonomous driving that over the past three years have stolen some of the thunder of the automotive establishment.

The most dramatic statement came from Daimler AG's Mercedes-Benz brand, which disclosed that in August a Mercedes S 500 'Intelligent Drive' researchvehicle autonomously retraced the 103-kilometer route between the German cities of Mannheim and Pforzheim navigated by Bertha Benz in 1888. Ms. Benz was the wife of Carl Benz, who patented the first self-propelled motor vehicle in 1886.

A navigation system, called Route Pilot, allowed the car to find its way safely to a destination on unrestricted, public roads.

The self-piloting S-Class includes a color camera mounted behind the windshield that could read stoplights, additional long-range radars to detect oncoming vehicles, a stereo camera with two lenses set apart to function like human eyes to detect distant objects, and a rear-facing camera designed to spot landmarks entered into a digital map.

On Tuesday, the chief executive of Continental AG, a German supplier of technology for the Mercedes self-driving S-Class project, said his company is lining up information technology partners for its self-driving vehicle systems development.

Continental's Elmar Degenhart also disclosed a new partnership with U.S. computer giant International Business Machines Corp. to develop systems to handle the data required to keep a self-driving car safely on the road. But he left unfilled a third leg of the self-driving technology stool -- teaming up with an Internet company.

'We feel a partnership with an Internet company makes sense,' Mr. Degenhart said. But he declined to comment on reports that Continental is in talks with Google to form an alliance in which the software company would supply mapping and other content for Continental's autonomous driving systems.

'We will try to complete our triangle by the end of the year,' he said, adding that Google is a potential partner.

Mr. Degenhart said his car-making customers are ramping up orders for technology that forms the building blocks of a self-driving vehicle, including radar vision systems.

By 2015, he said, Continental expects to deliver 10 million radar sensors, up from a projected 4.5 million this year.

Self-driving vehicle systems will likely be a 1 billion euro ($1.33 billion) a year business for Continental in the near term, he said.

Among the systems that could appear sooner in showrooms than a fully autonomous car is technology that would allow a car to navigate through construction zones, where barricades or equipment constrict the travel lanes, Mr. Degenhart said.

Other established automotive companies are getting in the race. French auto technology supplier Valeo SA showed a new 'Park4U' system that would allow drivers to leave a car at the entrance of a parking lot and use a smartphone to direct the vehicle to park itself.

TRW Automotive Holdings Corp. used the Frankfurt venue to promote new video and radar vision systems aimed at enabling 'semiautonomous driving.'

Nissan Motor Corp. late last month caused a stir in the industry by declaring that it will be ready to sell cars capable of fully autonomous driving by 2020. Volkswagen AG has also experimented with self-driving vehicles, principally through its Audi brand.

At Frankfurt, rival industry executives weren't as ready as Nissan to commit to hard dates for production.

'We have to take it step by step,' said Ian Robertson, global sales and marketing chief for BMW AG. Autonomous vehicle technology is advancing rapidly, but 'we are faced with a legislativeframework developed many decades ago.'

Currently available technology would allow drivers to take their hands off the wheel and allow the car to steer itself, but laws in most markets require that auto makers design such systems to demand that drivers grab the wheel at regular, short intervals.

General Motors Co. has disclosed its work on a 'super cruise' system that allows a vehicle to pilot itself at freeway speeds.

'Someday cars will drive themselves,' said John Capp, GM's director of Global Active Safety Electronics and Innovation. 'There's a reality that's not going to happen overnight.'

Among other things needed for a safe, fully autonomous car are faster computers and data networks, and robust answers to the challenge of how to alert a driver to respond in a situation the autopilots cannot handle.