Fuel economy of some of the 2012 Mercedes-Benz S Class models borders on dismal, yet for at least a couple of the models, this flagship luxury sedan can be a relatively green pick.
At the top of the model line, the performance-oriented AMG models are serious guzzlers. Even though the S 63 AMG fares best; its twin-turbo 5.5-liter V-8 managed EPA ratings of just 15/23 mpg. The twin-turbo V-12 cars are on another planet entirely, probably more due to their outdated five-speed automatic transmissions than anything: The S 600 and the S 63 AMG are both listed at just 12/19 mpg.
The greenest editions are the turbodiesel S 350 BlueTEC and S 400 Hybrid. The diesel edition, a new powertrain for U.S. buyers in this generation of S Class this year, offers up EPA ratings of 21/31 mpg, the highest highway ratings of the entire lineup. Not far behind is the S 400 Hybrid, with its lithium-ion battery pack and V-6 gas engine pairing; it's rated at 19/25 mpg.
The new twin-turbo, 4.6-liter V-8 engine available in the mainstream, executive-edition S 550 achieves excellent fuel economy, considering the size of the S Class. Officially rated at 15/25 mpg in the rear-drive S 550 and at 15/24 mpg in the S 550 with all-wheel drive, it's capable of more. We've clocked an indicated 25.5 mpg on a 300-mile interstate trip where speeds averaged nearly 80 mph.
On the bright side, the S Class models do score pretty well for smog-forming emissions; the S 65 earns a 6 out of 10 on the EPA Air Pollution Score.