The 2007 Mercedes GL450 engine is a DOHC, 4.7-liter V-8. You'd think even 335 horses might struggle a bit lugging 5300-plus pounds up an oxygen-deprived grade, but with max torque on tap at just 2700 rpm and the standard seven-speed automatic shifting away almost silently, the V-8 feels composed and quiet during a hill climb. On the highway the trip computer shows a 21-mpg average.




