The world's first plug-in hybrid supercar, the 918 Spyder, has just finished a series of driving trials, and now Porsche has revealed some impressive new specs for the car. We already knew the 918 Spyder would be able to reach speeds of around 200 miles per hour (including 90mph running only on its twin electric motors), but now Porsche has revealed that it will also feature 770 horsepower and fuel consumption of around 78 miles per gallon. The power is generated from a combination of a 570hp V8 engine and front and real axle mounted motors that produce 80 and 90 kilowatts of power each, respectively. And for those times when you run out gas, the 918 Spyder has a 15 mile, all-electric range. Porsche says that the recent tests "signal the final touches" for the car, though you won't see one on the road for quite a while — production is scheduled for September 2013, while customers in the US should be able to purchase their own towards the end of the year.