Gas mileage is a factor that rarely weighs in a pickup truck's favor. While the 2012 Chevy Silverado does better than most--much better, in the case of the Hybrid--it's still a relative laggard in overall fuel-economy ratings.
The Silverado's gas-only editions fare better with fuel bills than almost all other big trucks, save for the Ford F-150. The basic V-6 and V-8, though, aren't as good as Chevy's biggest seller, the 5.3-liter V-8. In part it's because the fleet-duty six and eight are sold with four-speed automatics, while the 5.3 gets a six-speed automatic. But the 5.3 also has cylinder-deactivation technology and an aero-smoothed XFE edition. The largest V-8 has the six-speed as well, but it's the lowest-rated by the EPA.