The 2008 Porsche Boxster is available as a 2-door, 2-seat convertible. Starting at $45,800, the 2008 Porsche Boxster Base (M5) is powered by a 2.7L , 6 -cylinder engine mated to a manual transmission that returns an EPA estimated 20-mpg in the city and 29-mpg on the highway. The top of the line 2008PorscheBoxsterS Limited Edition (M6) , priced at $ 59,900 , is powered by a 3.4L , 6 - cylinder engine mated to a manual transmission that returns an EPA estimated 18-mpg in the city and 26-mpg on the highway.