The Porsche 918 Spyder which started off as a concept won’t remain so for long, as it will be turned into a series production model in due time. It originally debuted as a concept earlier this year at the Geneva Motor Show, featuring a plug-in hybrid powertrain that is touted to deliver a whopping 78 miles per gallon. The concept saw a 500-horsepower V8 engine that worked in tandem with a pair of electric motors with 109 hp each, while the lithium ion battery is capable of delivering 16 miles of emissions-free driving from grid energy. While the powertrain was not expected to be altered much for production, Porsche didn’t announce when the 918 will be available for the rich and famous to bring one home, although it has been speculated that a €500,000 (about $650,000 USD) price tag should be about right. Well, if it ever makes its way Stateside, expect to gain from a $7,500 tax credit.