2025 Gmc Duramax Diesel Fuel Economy. View detailed gas mileage data for the 2025 gmc sierra 2500hd. Fuel economy of the 2025 gmc sierra.

Carbuzz tested a sierra 1500 denali ultimate with the optional duramax engine, one of the few diesel trucks left on the market now that ram killed the ecodiesel and ford no longer offers the. On a recent trip, i got 15.2 mpg unloaded with cruise set at 78.