The 2011 Mercedes-Benz M-Class SUV is a rare vehicle, in that it's offered with gas, diesel and hybrid versions. However, its greener side is offset by hugely powerful gas-quaffing V-8 models, one wearing the initials AMG.
In base trim, the V-6-powered, rear-drive Benz ML350 gets a rating of 16/20 mpg from the EPA. Adding on 4MATIC four-wheel drive drops its city fuel economy to 15 miles per gallon.
The best gas-mileage numbers of the lineup are posted by the ML450 Hybrid, at 20/24 mpg, and by the ML320 BlueTEC diesel, at 18/25 mpg. The diesel is widely available and 50-state legal, but the Hybrid only can be leased from Mercedes-Benz, and it's available only in limited numbers.
The M-Class steps out of green bounds in its V-8 versions. The ML550's fuel economy rates only 13/18 mpg from the EPA--but it's still better by a wide margin than the ML63 AMG. The extraordinarily powerful SUV sinks to 11/15 mpg, poor fuel economy that's worse than the largest Suburbans and Expeditions.