Sierra 2500 HD, 3500 HD and Savana

Diesel engines tend to be 30-35% more fuel efficient than similar sized gasoline engines. Diesel fuel has a higher energy density than gasoline. This density is the main reason diesel engines use heat from compression for ignition compared to gasoline engines which use a spark via a sparkplug to ignite the air-fuel mixture in the engine. Some recent diesel improvements include:

  • Increased power
  • Improved acceleration
  • Increased fuel efficiency
  • Reduced engine noise and shutter
  • Better cold-weather starting
  • Meet the same emissions standard as gasoline vehicles

Duramax diesel engine

Available Allison Transmission

This transmission is available in Sierra 2500HD and 3500HD models and handles the increased output of the DURAMAX® Diesel engine. We’ve increased the output shaft diameter and clutch capacities and beefed up the torque converter housing versus our previous–generation Allison. Customers depend on this transmission to get the truly heavy work done, especially considering it’s an Allison that drives the M1 tank.


Biodiesel is a highly processed and regulated fuel derived from vegetable oils and animal fats. Through a chemical process known as transesterification, the oils and fats are broken down into methyl esters (the biodiesel) and glycerin, a byproduct, which can be used to make soap or used in other applications.

To reduce carbon-dioxide emissions and stretch your fuel budget further, the Duramax 6.6L is engineered to operate on B20 biodiesel, a mixture of 20 percent biodiesel produced from domestic, renewable resources, and 80 percent petroleum diesel.

Duramax diesel engine in truck

Duramax 6.6L engines. The LML Duramax Diesel engine is available on Sierra HD models. The Savana LGH Duramax Diesel is offered on 3500 models.


To help reduce carbon dioxide emissions, the Duramax Diesel 6.6L V8 Turbo can run on B20 biodiesel, a mixture of 20 percent biodiesel produced from domestic renewable resources, and 80 percent petroleum diesel.


The available Duramax Diesel engines are made in Dayton, Ohio and based on GM testing can provide a highway mileage range up to 680 miles one a single tank of fuel. The GMC Savana's available Duramax 6.6L V8 is the most powerful diesel engine in its class.