Ford Motor is announcing today that it's going to be the first U.S. automaker to add technology to all its conventional cars to shut off their engines at stoplights.

The so-called start-stop technology will cut gas use by 4% in most cars, and by up to 10% in vehicles in crowded cities that spend a lot of time idling at stoplights. Every time a driver comes to a stop, the engine will shut off. It will start again automatically as soon as the driver presses the accelerator.

The technology puts Ford well on its way to meeting more stringent fuel-economy standards in the U.S. for 2016 that could make the same technology pretty standard on vehicles by most automakers. It's a cheap way to save more gas - at least compared with hybrids and battery-electric cars.

Start-stop technology can already be found in the Ford Fusion hybrid and Ford Escape hybrid and some of the cars that Ford sells in Europe:

"For the driver, Ford Auto Start-Stop provides extra fuel efficiency without inconvenience, as it works completely automatically," said Barb Samardzich, Ford vice president of powertrain engineering. "And, just like in our hybrid vehicles, the heater and air conditioner work as normal so drivers will not sacrifice comfort."