A fourth-generation, sportier Toyota Prius, due more than a year from now, “will have a new type of hybrid system” as well as Toyota’s most thermally efficient gasoline engine.

Toyota’s updated top-selling hybrid that’s been offered in the U.S. since 2000 will be based on a modular platform called Toyota New Global Architecture (TNGA).

The company’s design chief said the new Prius will be revolutionary outside and in with lower center of gravity for handling and sportier appearance while actually offering better gas mileage and emissions.

Its gas engine is said to be 40-percent efficient, outdoing the 38.5 percent of the present Atkinson-cycle 1.8-liter four.

Lithium-ion batteries will replace nickel-metal-hydride, according to a Automotive News reporting from Japan where the new car will continue to be built.

Toyota’s TNGA architecture will enable commonization of many components to cut engineering time, costs, and allow flexibility in manufacturing.

Whether the Prius will be the first TNGA vehicle or merely one of others was not stated.

Last year Toyota lost market share but still sold over 1 million hybrid vehicles and is by far the number-one hybrid seller in North America and the world.

Toyota’s own success has spurred a raft of competitors either directly, such as the Ford C-Max Hybrid, or indirectly from other full hybrid sedans and other types that offer relatively good mileage and other benefits.

Today there are close to 45 hybrids sold in the U.S. and Toyota has meanwhile said it will push its hybrid agenda all the harder.

That underlying reality is driving the new Prius’ development, and that also of a plug-in version expected to offer significant improvements as well.