The 2014 S-Class arrived in America in the fall of 2013 with just a single drivetrain at first, leaving the most fuel-efficient models from the prior year on hold.
Official U.S. EPA gas mileage ratings place the S550, powered by a twin-turbo, 4.6-liter V-8, at a fair 17 mpg city, 25 mpg highway, and 20 mpg combined. The 2014 figures make the new S550 a notch better than last year's--though it's still a bit thirsty in the grander scheme.
The S550 4Matic (all-wheel-drive) scores 16/26 mpg city/highway, and the S63 AMG scores 15/23 mpg city/highway.
As a guideline, last year's S550 was rated at 15/25 mpg in the rear-drive S550 and at 15/24 mpg in the S550 with all-wheel drive. In long-distance interstate driving, we've seen 25.5 mpg even when cruising at nearly 80 mph with this engine and the standard seven-speed automatic.
In the offing are new versions of the S350 BlueTEC turbodiesel, and a hybrid. But that gas-electric model won't simply be a restyled S400 Hybrid with a carryover drivetrain--it is a new S500 plug-in hybrid, recently revealed at the 2013 Frankfurt Auto Show but not yet rated for the U.S. market. European gas mileage figures place it at up to 78 mpg, but those figures don't translate well to EPA ratings.