The first SARTRE (SAfe Road TRains for the Environment) road train on a public highway among other road users was performed successfully in May 2012. The road train was comprised of a Volvo XC60, a Volvo V60 and a Volvo S60 plus one truck automatically driving in convoy behind a lead vehicle.

Smart cars obediently followed the leader in the first public test for a futuristic "road train" concept. The idea of having networked cars follow a truck could pave the way for tomorrow's self-driving cars to drive together.

The recent test featured a Volvo XC60 compact crossover SUV, a Volvo V60 sports wagon, a Volvo S60 compact executive car and a truck all connected wirelessly to a lead truck. Such networked "talking" allowed the cars to mimic the accelerating, braking and turning of the human driver in the truck — all while traveling at 53 mph (85 kilometers per hour) on a public highway in Spain.

"People think that autonomous driving is science fiction, but the fact is that the technology is already here," said Linda Wahlstrom, project manager for the SARTRE project at Volvo Car Corp. "From the purely conceptual viewpoint, it works fine and road train will be around in one form or another in the future."

The SARTRE (Safe Road Trains for the Environment) project aims to allow convoy drivers to work on their laptops or relax with lunch instead of paying attention to long stretches of road. The networked car demonstration also suggests how many self-driving cars together could lead to safer and more efficient travel because of smooth, coordinated acceleration and braking. [5 Ways Self-Driving Cars Will Make You Love Commuting]

"Apart from the software developed as part of the project, it is really only the wireless network installed between the cars that set them apart from other cars available in showrooms today," Wahlstrom said. She added that the cars traveled about 124 miles (200 kilometers) during the latest test.

SARTRE vehicles have covered more than 6,200 miles (10,000 kilometers) since the European project began in 2009. The successful Spanish road trip will lead to the next phase of the project focused on fuel consumption.

The lead vehicle in the SARTRE convoy still relies on a human driver, but that could easily change to an autonomous car. Google already has plans to expand its testing of self-driving cars beyond the San Francisco Bay Area to road tests in Nevada.

This story was provided by InnovationNewsDaily, a sister site to LiveScience. Follow InnovationNewsDaily on Twitter @News_Innovation, or on Facebook.