Toyota Motor Corp. released details for its fourth-generation Prius yesterday, promising that improvements in the battery, engine, wind resistance and weight mean better mileage for the world's top-selling hybrid car.

It gets up to 40 kilometers a liter under Japanese tests, which translates to more than 93 miles per gallon, a 20 percent improvement from the 2015 model. In the U.S., it gets 55 mpg in combined city and highway driving, about 10 percent better.

The Prius, which debuted in 1997, goes on sale in Japan in December, and rolls out in the U.S. and other markets early next year. A price was not announced, but it's expected to stay in the same range.

The Prius now starts at about $24,000 in the U.S. and 2.4 million yen ($20,000) in Japan. A hybrid switches back and forth between a gasoline engine and an electric motor to deliver a super-efficient drive.