There are several ways to increase fuel mileage for a Duramax diesel, including making adjustments to the fuel injection system, tuning the engine, changing gear ratios or installing hub spin free kits. The benefit of each approach varies greatly depending on the specific vehicle, use and driving style.
When maximum power is not necessary, locking hub or spin-free kits such as those offered by Yukon Gear and Axle engage or disengage the front wheel hubs for reduced drag and greater fuel economy. Another option from Yukon is to change the gear ratio in the differential. A high ratio, which is numerically lower, reduces low-end torque but increases fuel economy. Engine tuning and fuel injection services can also help increase fuel economy. Companies such as Heath Diesel and Diesel Domination sell aftermarket products and services to help with those adjustments.