2025 Denali Duramax. Detailed specs and features for the 2025 gmc sierra 2500hd diesel denali ultimate including dimensions, horsepower, engine, capacity, fuel economy, transmission, engine. The 2025 gmc sierra hd denali ultimate, refreshed for the 2025 model year, is gmc's most premium, luxurious and technologically advanced truck yet.
The sierra 2500hd denali ultimate looks to elevate the brand’s premium status, with a refreshed duramax, a new exterior, and more. The 2025 sierra hd denali has the powerful capability to pull your world while still offering the premium amenities you expect from a gmc denali truck.