What You Need To Know 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 ...

Several GM vehicles have been offered with a Duramax diesel engine over the years, the most notable example being the Chevrolet Silverado and its GMC counterpart, the Sierra. Duramax-powered ...