The 2012 Mercedes-Benz M-Class is available as a 4-door, 5-seat sport utility. Starting at $48,990, the 2012 Mercedes-Benz M-Class ML 350 is powered by a 3.5L , 6 -cylinder engine mated to an automatic transmission that returns an EPA estimated 17-mpg in the city and 22-mpg on the highway. The top of the line 2012Mercedes-BenzM-ClassML 550 , priced at $ 57,590 , is powered by a 4.7L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 15-mpg in the city and 20-mpg on the highway.