The 2006 Jaguar XK8 is available as a 2-door, 4-seat coupe. Starting at $74,830, the 2006 Jaguar XK8 Convertible is powered by a 4.2L , 8 -cylinder engine mated to an automatic transmission that returns an EPA estimated 18-mpg in the city and 26-mpg on the highway. The top of the line 2006JaguarXK8Coupe , priced at $ 69,830 , is powered by a 4.2L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 18-mpg in the city and 26-mpg on the highway.