Porsche is pushing ahead with additional plug-in hybrid vehicles as mainstays of its lineup. The German automaker will debut a plug-in hybrid as the flagship model of its Cayenne series. The Cayenne Turbo S E-Hybrid and the Cayenne Turbo S E-Hybrid Coupe will each feature a total system output of 500 kW, powered by a 4L V8 engine in combination with an electric motor and eight-speed Tiptronic S transmission, according to a new report from Green Car Congress. The sister vehicle of the two turbo hybrid Cayennes, the Cayenne E-Hybrid Coupe, will carry a slightly less powerful system, with a total output of 340kW. The vehicles can achieve speeds up to 135km/h (~85 mph) on only electric power. Green Car Congress has the story. Read more.