The demonstration at Honda's test center outside Tokyo previews what is shaping up as the next phase of automotive safety: vehicles that talk to each other and the highway system itself.
They silently send or receive warnings from other cars in close proximity. Or they pass information back and forth to sensors along the roadway that become part of a real-time database.
They tell of their approach to an intersection, warn about hazards ahead or keep an inattentive driver from running a red light, all with the goal of preventing accidents.
Around the world, major automakers from General Motors to BMW see the idea of a transportation system that can communicate as a major safety breakthrough.
"It does seem like it's straight out of a science-fiction movie," says Robert Strassburger, vice president of vehicle safety for the Alliance of Automobile Manufacturers. "But it's happening already."
Seat belts require people to buckle up. Air bags work only after the crash. Only so-called intelligent transportation systems can prevent an accident from happening in the first place. They could be especially valuable in stopping crashes at intersections or when vehicles swerve off the road.
Intelligent transportation also offers a lucrative side benefit: the sharing of information that could ease traffic congestion. Traffic jam data could be gathered from the electronic messages of cars themselves, not just from sensors in roadways.
On Tuesday, Motorola announced at ITS America's convention in San Francisco that it signed its first contract with the Michigan Department of Transportation to deploy a test system that connects vehicles to the roadside and to one another. Trials have started in the Detroit suburb of Southfield.
Japanese automaker Nissan says it expects up to 10,000 motorists to participate in a test of an intelligent-transportation system starting next year in a region south of Tokyo.
Cars are already being built with many of the devices that can be adapted to make them chatty. For instance, luxury cars can come equipped with more than two dozen computers that keep track of everything from the outside temperature to whether the headlights are on.
"If you had cars talking to each other, it would tell people three, four or five cars back" that traffic has stopped ahead, says John Mendel, a senior vice president in Honda's American operation.
Short-distance wireless systems, which would likely be at the heart of an intelligent-transportation network, are also starting to show up. They are used by some toll road and bridge operators so that drivers can roll through toll booths without stopping to pay. Transmitters in cars wirelessly record the vehicles' passage so drivers can be billed by mail.
Experts say that's just the start. Cars could detect other vehicles not heeding a red light. If a car slips on ice, intelligent systems could not only inform other drivers but send a notice through the receivers alongside the highways to road crews that salt or sand is needed. Such systems could even be programmed to stop cars before an accident occurs — without driver involvement.
Likewise, Nissan fears drivers could become complacent if they believe their cars will automatically extract them from danger, The USA reports.