I just found this though I don't know how relevant it might be
2013 Update: GM hasn't followed through on its promise of a diesel engine... yet.
On June 15, 2007, General Motors announced that it will produce a new 4.5-liter Duramax tubodiesel engine for its light duty trucks built after 2009. That list includes the Chevy Silverado, the GMC Sierra, and the HUMMER H2.
The new diesel engine is compact, and will fit in the same space used for today's small-block V-8 gas engine. We won't have exact specs for awhile, but GM projects a rating of at least 310 horsepower and 520 lb-ft of torque for the engine.
GM says owners will see a 25-percent increase in gas mileage, and that the new turbodiesel will produce about 13-percent less carbon dioxide and 90-percent fewer NOx emissions than comparable gasoline engines.
The opportunity to own a truck equipped with a turbodiesel engine is good news for those of us looking for the increased towing capability those engines offer -- but don't want or need a heavy duty truck.
Charlie Freese, Executive Director of GM Powertrain Diesel Engineering, made this statement to the press:
"This new V-8 is not only a clean diesel meeting the toughest emissions requirements in North America, it also delivers an effortless performance feel because of its high torque across the speed range. It is also significantly quieter than other diesels on the road today, with noise and vibration performance approaching gasoline V-8 levels."
GM's Duramax turbodiesel line was introduced in 2001, and has boosted sales of the company's medium and heavy duty pickup trucks. It's also used to power GM's large vans and commercial vehicles.
General Motors isn't the only automaker developing a clean diesel for its light duty trucks. Nissan will put a diesel in its Titan truck and Ford plans to add diesel as an option to its half-ton pickup trucks.