NISSAN Motor Co will soon sell cars that push back when drivers try to put the pedal to the metal. It has also developed a test model packed with additional sensor technology to make vehicles "crash-free."

The features unveiled this week by Nissan are the latest among recent efforts by the world's auto makers to vamp up their images.

Nissan's collision-free prototype has sensors at its back and side that turn on alarms and brakes to help avoid collisions. The system also helps the vehicle maintain a safe distance with the car in front, as well as preventing it from veering off its lane, Nissan said yesterday.

Nissan has said it hopes to halve the number of traffic accidents or serious injuries involving Nissan vehicles in Japan by 2015 compared to 1995 levels.

Nissan's "ECO Pedal" system, promoted as being both green and safe, makes the gas pedal press upward when it senses motorists are speeding up too quickly.

Nissan said on Monday that the system, available from next year, could help drivers improve fuel efficiency 5 to 10 percent.

The system calculates the most efficient rate of acceleration in a vehicle based on how fast fuel is being burned and other factors and causes the gas pedal to push back to alert overzealous drivers. A meter on the dashboard flashes and changes colors to help drive the message home.

Part of the firm's strategy for reducing carbon-dioxide emissions is modifying driving behavior. Drivers can also opt to switch the system off.