Toyota also showed a new feature that helps the driver brake harder to prevent bumping into the vehicle in front. Toyota officials said drivers often fail to push hard on their brakes in such situations because they get into a panic.
Toyota said the technology will be available "soon," without giving a date, and hinted it will be offered for Lexus luxury models. Luxury models already offer similar safety features such as automatic braking. Technology involving precise sensors remains expensive, sometimes costing as much as a cheaper Toyota car.
Toyota has also developed sonar sensors that help drivers avoid crashing in parking lots. One system even knows when the driver pushes on the gas pedal by mistake instead of the brakes, and will stop automatically.
Rear-end collisions make up 34 percent of car accidents in Japan, comprising the biggest category, followed by head-on collisions at 27 percent.
Cars that stop and go on their own, avoiding accidents, are not pure science fiction, experts say.
Alberto Broggi, professor at the University of Parma and an expert on intelligent transportation systems, said the idea of the accident-free cars is "very hot," and probably within reach on some roads within several years.
"I'm sure we will arrive to such a technology even if I don't know when exactly," he said.
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