To make America's roads safer, cars should constantly talk to each other over a wireless car-to-car network rather than just relying on drivers to see what others are doing.

Automakers and the government have been researching the technology for years. Now the National Highway Traffic Safety Administration has formally proposed a rule requiring a uniform industry-wide system that would be put in all new cars. If the rule is approved, NHTSA said, it would take two to four years for the technology to be in all new cars.

Experts have long talked of the life-saving potential of the technology.

Instead of a driver having to see and react to a car stopping ahead, for instance, any application of the brakes in one car would send an electronic signal to other cars around it. Those cars could then warn drivers that a car ahead is stopping even if the vehicle is out of sight. Similarly, drivers could be warned not to turn left across traffic because of on-coming cars. Cars with automated driving technologies, like automatic braking, could respond on their own to the signal.

The technology, known in the industry as V2V, could also be combined with automated driving technologies to provide better and quicker responses that would be possible by relying on radar and cameras. Even with human drivers, the technology could help avoid 80% of crashes involving sober drivers, according to NHTSA.

NHTSA officials have compared the potential life-saving importance of the technology to that of seatbelts and electronic stability control, auto safety features that have been credited with saving many thousands of lives.

V2V technology could save about 1,000 lives a year and avoid 190,000 to 270,000 crashes, according to NHTSA. The addition of V2I -- vehicle-to-infrastructure -- technologies could save even more lives. NHTSA said it is planning to soon issue proposed rules for V2I technologies so cars could talk to things like stop signs, red lights.

Automakers would be required to have the technology in new cars and consumers would not be able to legally turn it off, according to NHTSA. Drivers would be given the option to turn off warnings and automated responses, though.

Once it's installed on significant numbers of vehicles, the technology could also improve traffic flow and thereby save fuel, the agency said.

The proposed rule would apply only to passenger vehicles, but the auto safety agency is also looking into its application to trucks and buses.

The data sent between and among vehicles would not identify individual vehicles, NHTSA said, so privacy would not be compromised. The agency could not say whether police agencies would be able to use the data stream for general traffic enforcement. NHTSA also issued proposed guidance for security methods to protect the V2V network from hackers