The Chevy 8.1-liter engine gets an average of 14 miles per gallon, or mpg, in optimum driving conditions. Most owners report a range of nine to 10 mpg in town and 11 to 13 mpg on the highway.
The fuel efficiency of this engine depends on several factors, such as driving conditions, the condition of the vehicle and whether it's hauling any extra weight, such as a boat or a camper. The ethanol content of the fuel may also impact the fuel efficiency. Any stresses on the engine reduce the fuel efficiency as well.
The 8.1-liter engine is ideal for vehicles that are treated as workhorses. To maximize fuel efficiency, it's important to keep the vehicle in good working order and to follow the maintenance guidelines set forth by the manufacturer.