The 2013 Mercedes-Benz GL lineup shaves weight wherever possible, with aluminum body panels, suspension pieces, and body bracing. It adopts electric power steering and a more efficient electrical structure, and adds gears to its automatic transmission, all in the interest of saving fuel.
Still, it's not that much more frugal than before, though the diesel model absolves some of the sins of the big V-8s, especially the coming GL63 AMG.
The turbodiesel's one of the GLs we recommend most often, primarily because it's the only one to break the 20-mpg combined barrier. As estimated by Mercedes-Benz--awaiting official confirmation by the EPA--the GL 350 BlueTEC is rated at 18 miles per gallon city, 24 miles per gallon highway. It's improved over the prior generation of BlueTEC GLs, and like most diesel vehicles, we've found it easier to come nearer to those figures than with competitive hybrid vehicles.
The rest of the GL lineup is marginally better at saving gas. The GL 450 hasn't received a combined rating, but it's pegged at 14/19 mpg. The GL550's predicted at 13/18 mpg, with a 15-mpg combined rating. And the upcoming GL63 AMG? It's expected to settle in at a low 12/17 mpg.