GMC Sierra HD AT4

GMC Sierra HD AT4 models are off-road-oriented variants that combine enhanced capabilities with GMC’s premium refinement to practically complement an authentic outdoor lifestyle

The performance-enhanced pickups made their debut with arrival of the fourth-generation Sierra HD model, and are expected to receive a refresh for the 2023 model year.

GMC Sierra HD AT4 Quick Facts
Model Year Availability	2020 – Present
Engine(s)	6.6L L8T V8,6.6L L5P Duramax
Transmission(s)	6-Speed Auto, Allison 10-Speed Auto
Drive Wheels	Four-Wheel-Drive
Availability	U.S.A., Canada, Mexico, Middle East

The GMC Sierra HD AT4 debuted for the 2020 model year, when the fourth-generation heavy-duty pickup truck lineup entered the market. Like all AT4 models, Silverado HD AT4 features were highlighted by off-road components, and included:

Off-road suspension, Rancho Shocks, skid plates, Eaton locking rear differential
Eighteen-inch wheels wrapped with Michelin all-terrain tires
- 20-inch wheels available
Traction Select System with specific Off-Road mode
Hill Descent Control and Hill Start Assist
Segment-exclusive 15-inch diagonal Head-Up Display with Off-Road Inclinometer
HD Surround Vision for low-speed views of vehicle surroundings

It’s worth highlighting the fact that all of GM’s heavy-duty pickup offerings are fitted with a standard ride height, meaning Sierra HD AT4 models are not equipped with a lift kit.

For the 2021 model year, the Sierra HD AT4 pickup received a few minor changes, including the addition of the AT4 high clearance step (LPO-level item), high-gloss Black mirror caps, a new AT4 Premium Plus Package, and revisions to AT4 Preferred Package contents.

Notably, the 2022 GMC Sierra HD AT4 sees no changes, though it is expected to receive a refresh for the 2023 model year.