The 2008 Jaguar XJ is available as a 4-door, 5-seat sedan. Starting at $63,835, the 2008 Jaguar XJ XJ8 is powered by a 4.2L , 8 -cylinder engine mated to an automatic transmission that returns an EPA estimated 16-mpg in the city and 25-mpg on the highway. The top of the line 2008JaguarXJVanden Plas , priced at $ 76,085 , is powered by a 4.2L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 16-mpg in the city and 25-mpg on the highway.