2011 Infiniti M56 V8 returns 28.2 mpg in recent testing

2011 Infiniti M – Click above for high-res image gallery

If someone claimed that you could take a two-ton vehicle and stuff it with a 420 horsepower V8 yet still get over 28 miles per gallon, you may consider calling their bluff. But what if it turned out to be true?

Meet, again, the 2011 Infiniti M56 is rated at 420 hp and 417 pound-feet of torque. The 5.6-liter V8 resides within the 4,000-plus pound vehicle. Through the use of direct injection, as well as a driver-selectable Eco mode, this Intiniti can go from drag strip warrior to fuel economy champ thanks to a little button.

Technically, the M56 fits into the sports sedan class but Infiniti saw an opportunity to offer something that few of its competitors do, an eco mode that boosts gas mileage to four cylinder levels. At the push of a button, the M56 becomes a fuel sipper. Eco mode is one of four driver-selectable modes: sport, standard, snow and eco.

In eco mode, the throttle response is dampened considerably via the eco pedal. The eco pedal offers considerable resistance to driver input and encourages you to refrain from pushing on the accelerator with any amount of force. During a recent test drive, Ward's Auto noted that the pedal, though annoying, helped them achieve a remarkable 28.2 miles per gallon. For comparison purposes, Ward's also tested the lesser Infiniti M37 with eco mode engaged and only managed 26.8 mpg over the same loop.

Engaging eco mode means sacrificing some of the vehicle's amazing power in return for efficiency untouched by comparable V8s, it also means that a Prius or two may pass you on the highway, but combining performance with the frugality of a Honda Civic into one single package is worth the sacrifice.

[Source: Ward's Auto – sub. req.]