Thanks to a new lineup of direct-injection V-6 and V-8 gasoline engines, the 2012 Mercedes-Benz E Class models are significantly more fuel-efficient than last year's models.
E350 models now rate up to 20 mpg city, 30 highway, while E550 models get up to 17/27. 4Matic all-wheel drive drops estimates by up to several miles per gallon, depending on the model and the body style.
Even considering the improvements in those gasoline engines, you're still going to keep things clean--and the most fuel-efficient--with the E350 BlueTec Sedan. At 21 mpg city and 32 mpg highway, it's the greenest of the E Class bunch.
And if you're even reading this section, you probably aren't considering the high-performance E63 AMG models. Rated as low as 15 mpg city, 23 highway, they're guzzlers, albeit very rewarding ones.