View detailed gas mileage data for the Chevrolet Silverado HD. Use our handy tool to get estimated annual fuel costs based on your driving habits. Find and Compare Cars ; Personalize · Find a car ; Bifuel Natural Gas. 8 cyl, L, Automatic 4-spd. Compare · Regular Gas. Combined MPG combined. city/. In comfort, reliability, fuel economy, design and value, you can't beat this truck. The Duramax Diesel with the Allison automatic transmission is incredible.
My 09 gmc duramax 4dr long box with a tuner and bigger exhaust gets mpg at 60 mph mpg at 70 unloaded and mpg at 80 mph. Towing up to 10k lbs i. Fuel Economy of GMC Vehicles ; Compare ; Combined MPG combined. city/highway. MPG. City MPG city. Highway MPG highway. gals/ miles ; Not. I had a same truck crew cab and could get about 16 mpg on average. When towing big trailer it went down to.