Hybrids and big V-8s balance out the 2011 GMC Sierra's green scores, with the Hybrid model earning best-in-class numbers, while the luxury-edition V-8 cuts those figures by at least a third.
The Sierra lineup for 2011 includes four V-8 engines and one V-8 with hybrid motors and batteries. The Sierra Hybrid earns the best fuel economy of all, predictably, with its EPA-rated 20/23 mpg. From there, it's a gradual descent into the mid-teens of fuel economy ratings. With the 5.3-liter V-8, the Sierra is rated at 15/21 mpg--which is better than the 4.3-liter V-6's 15/20 mpg, in part due to the six-speed automatic that's paired with the V-8, versus the four-speed that twins with the six.
The workhorse GM 4.8-liter V-8 checks in at 14/19 mpg, while the luxuriously powerful and sonorous 6.2-liter V-8 quaffs unleaded at the rate of 13/18 mpg.GM doesn't offer a diesel on the light-duty Sierra.