The 2006 Porsche Boxster is available as a 2-door, 2-seat convertible. Starting at $45,000, the 2006 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 2006PorscheBoxsterS (M6) , priced at $ 54,700 , is powered by a 3.2L , 6 - cylinder engine mated to a manual transmission that returns an EPA estimated 19-mpg in the city and 27-mpg on the highway.