The 2014 Mercedes - Benz E250 BlueTec is the clear fuel economy leader of the 2014 E-Class lineup, which also includes 3.5 - liter V - 6 E350 models, an E400 Hybrid model with a V - 6 mated to an electric motor, and the 5.5 - liter V - 8 E550 models. (automobilemag.com)