Toyota says its all-new 2016 Prius sets a new bar with an expected 10% improvement in fuel economy or 55 m.p.g. for the core models of a family of hybrids already known for their efficiency. The fourth-generation Prius will go on sale in Japan in December and hit U.S. showrooms early next year. Pricing has not been announced. It debuts in a rare cycle of low gasoline prices which has suppressed the sales of hybrid and electric vehicles. But at some point, gas prices are expected to rise again which pushes consumers to buy fuel-sipping vehicles. Read more 2016 Toyota Prius to get 55 m.p.g.