In one Reddit discussion about the fuel economy of the 2024 GMC Sierra 2500HD Denali Ultimate 6.6 Duramax, commenters wrote that they usually get between 13 and 17 mpg when city driving and 17-23 ...

Duramax LLY (2004 - 2005) Truck ... system to the Duramax and added a ninth fuel injector specifically for the DPF regeneration process. ... its claimed 15 city mpg besting the LMM's roughly 12 mpg.

GM's new 6.6-liter "LML" Duramax V-8 turbodiesel for its 2011 Chevrolet Silverado and GMC Sierra Heavy Duty pickups will be capable of burning B20 biodiesel fuel, according to a GM press release ...