Of the about nine million gasoline-electric hybrid vehicles on roads around the world today, eight million are from Toyota and half of those are Prius models. In 18 years of production, the once novel Prius has become mainstream. Now in its fourth generation, the new Prius brings bolder styling, better handling, higher performance and improved fuel efficiency, says Toyota. Its hybrid system components have been made smaller and lighter, including the electric motor, transaxle, power control unit and battery. Toyota says its new low-friction engine achieves up to 40 percent thermal efficiency (the ratio of the work done by an engine to the total quantity of heat contained in its fuel), the world’s highest for a mass-produced engine.