Mercedes reckons the GL450 is the ideal vehicle for what it sees as a full-size traditional family and as such, provides for occasions that involve towing a boat/horse trailer or require the cargo capacity for visits to a home-improvement center. The GL-Class is a 4-door, 7-passenger luxury sport-utility, available in 3 trims, ranging from the GL350 BlueTEC to the GL550. Upon introduction, the GL450 is equipped with a standard 4.6-liter, V8, 335-horsepower engine that achievest achieves 13-mpg in the city and 17-mpg on the highway. A 7-speed automatic transmission with overdrive is standard on both trims.