Toyota's plug-in hybrid launch delayed by several months

Toyota leads the industry in hybrids, which switch between a gas engine and an electric motor.

The company is promising a whopping mileage equivalent to 120 miles per gallon, calculated including how far the vehicle goes as an electric car, without a drop of gas, for Prius Prime called Prius PHV in Japan.

Other major automakers offer plug-ins, including General Motors Co., Ford Motor Co. and Volvo, as well as electric cars from Tesla and Nissan Motor Co.

The plug-in battery is an expensive component and falling oil prices have been eroding the appeal of hybrids and plug-ins.