YOKOSUKA, Japan - Some Nissan cars will soon come with a gas pedal that lifts to warn of possible collisions, and the cars will automatically stop if a driver's foot leaves the accelerator in response to the warning.

The technology combines radar sensors and a computer system to assess a car's speed and the distance to a vehicle in front, Nissan Motor Co. said Monday. Cars with the new safety features will be available this year in Japan, and next year in the U.S.

The idea was to make a car that judges dangers on its own, like an animal, so car and driver can work together, said Nissan senior manager Yousuke Akatsu.

"It is almost like riding a horse, the way the rider can have a dialogue with the horse," he said.

As soon as a driver releases the gas pedal, the brakes kick in automatically to bring the car to a stop, Mr. Akatsu said. The car will keep going if the driver continues to step on the gas pedal.

Nissan also showed an experimental system that measures alcohol levels in a driver's sweat from sensors in the gearshift. The system stops short of locking the ignition but issues a warning in an electronic voice.

Nissan said drunken driving caused 611 fatal accidents in Japan last year. That's half the number of a decade ago, but 10 percent of fatal accidents.

The car also recognizes if a driver is drifting between lanes and has a computerized camera that monitors blinking to check if a driver is drunk or drowsy.

Nissan officials said people probably wouldn't buy such an intrusive car, but that the technology might have commercial uses, such as in delivery trucks and taxi cabs.

More practical is the lane departure prevention technology, which swivels a car back into its lane if it swerves off. The lane technology is being offered later this year in the U.S. on the Infiniti EX luxury model.

Nissan also showed a dummy crash test to demonstrate bumper sensors that release a hinge to lift the engine hood slightly and soften the impact if a pedestrian is hit.

People hit by sporty models can be hurt more seriously, because the cars are lower to the ground and have little space between hood and engine. Raising the hood on impact helps absorb the shock and reduces the potential injury to a pedestrian.