The 2015 Porsche 918 Spyder is available as a 2-door, 2-seat convertible. Starting at $845,000, the 2015 Porsche 918 Spyder Base is powered by a 4.6L , 8 -cylinder engine mated to an automatic transmission that returns an EPA estimated 20-mpg in the city and 24-mpg on the highway. The top of the line 2015Porsche918 Spyderw/Weissach Package , priced at $ 929,000 , is powered by a 4.6L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 20-mpg in the city and 24-mpg on the highway.