YOKOSUKA, Japan — Some Nissan cars will soon come with a gas pedal that lifts to warn of possible collisions, while the cars will automatically stop if drivers take their foot off 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 this week. 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 a friendly animal, so machine 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 drivers lift their foot off the gas pedal, the brakes kick in automatically to bring the car to a stop, 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 comes with 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 the technology may 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 more hurt more seriously and easily, because the cars are lower to the ground and have lean designs with little space between the hood and engine. Raising the hood on impact helps absorb the shock and reduces the potential injury to a pedestrian.

The pop-up hood will be offered in Japan this year, Nissan said. Jaguar, owned by Ford Motor Co., and Honda Motor Co. already offer the feature.