The 2008 Mercedes-Benz GL-Class is available as a 4-door, 7-seat sport utility. Starting at $53,400, the 2008 Mercedes-Benz GL-Class GL 320 CDI is powered by a 3.0L , 6 -cylinder engine mated to an automatic transmission that returns an EPA estimated 18-mpg in the city and 24-mpg on the highway. The top of the line 2008Mercedes-BenzGL-ClassGL 550 , priced at $ 77,375 , is powered by a 5.5L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 13-mpg in the city and 17-mpg on the highway.