The 2000 Mercury Grand Marquis is available as a 4-door, 5-seat sedan. Starting at $22,605, the 2000 Mercury Grand Marquis GS is powered by a 4.6L , 8 -cylinder engine mated to an automatic transmission that returns an EPA estimated 18-mpg in the city and 25-mpg on the highway. The top of the line 2000MercuryGrand MarquisLS , priced at $ 24,505 , is powered by a 4.6L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 18-mpg in the city and 25-mpg on the highway.