The upcoming 2010 GMC Sierra and its twin brother Chevrolet Silverado powered by the same 5.3-liter V8 engine will sport significant improvements in both city and highway driving cycles.
Official EPA estimates state that the refreshed models will have their fuel economy enhanced from 14 / 20 mpg to 15 / 21 mpg in city and highway cycles respectively, which is, again, 7 and 5 percent better than the current Sierra and Silverado can deliver in ideal conditions.
GM says that the most fuel efficient 2010 XFE models will return the same 15 mpg in the city, but will have their highway mileage improved by 4.54 percent to 22 mpg (10.69,) which is really good for such a huge truck with an aerodynamics similar to that of a brick.
According to the company, the increase in fuel efficiency was achieved due to some minor tweaks in their Active Fuel Management system, which is capable to shut down half of the V8′s cylinders in lighter driving conditions, more efficient gear ratios in its six-speed transmission and this sort of stuff.
Although the 2010 Chevrolet Silverado and GMC Sierra offer only slight fuel efficiency improvement comparing to their main competitors, the new Ford F-150 5.4L and the 2009 Dodge RAM 1500 5.7L, the improvement is nevertheless more than welcome now, when the oil prices seem to go through the roof again.
See also: 2009 Chevrolet Tahoe XFE