2026 GMC Sierra HD AT4
2026 GMC Sierra HD AT4 OVERVIEW 
2026 GMC Sierra HD AT4 For Sale
- Exclusive Jet Black interior with Kalahari accents, and heated and ventilated perforated front leather seating surfaces
- Off-Road Suspension Package with twin-tube Rancho shocks and skid plates
- Exclusive 20" gloss-black aluminum wheels with available BFGoodrich® off-road tires
- Adaptive Cruise Control* with trailering*
2026 GMC Sierra HD AT4 MODELS
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Sierra HD AT4
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Sierra HD AT4X
GMC Sierra HD AT4 For Sale
2026 GMC Sierra HD AT4 PERFORMANCE 
DURAMAX 6.6L TURBO-DIESEL V8 ENGINE
The Sierra Heavy Duty off-road truck’s available Duramax 6.6L Turbo-Diesel V8 engine features an efficient turbocharger and 10-speed automatic transmission.
AT4 OFF-ROAD READINESS
The AT4 off-road work truck features an off-road suspension with twin-tube Rancho shocks, skid plates and Hill Descent Control, which uses antilock braking to help you maintain control.
AT4X OFF-ROAD PROWESS
The AT4X off-road truck is prepared for the challenges of the trail with ground clearance of 11.6 inches, an approach angle of 31.6 degrees and a 25.7-degree departure angle.
2026 GMC Sierra HD AT4 APPEARANCE 
AT4 GRILLE
Stand out with AT4’s bold front-facing exterior design and LED projector headlamps with animated sequences.
AT4X EXTERIOR
35" Goodyear Territory MT tires and a factory-installed 1.5" suspension lift on Sierra HD AT4X and AT4X AEV Edition provide serious traction and clearance.
20" AT4 WHEELS
Sierra HD AT4’s 20" gloss-black aluminum wheels with available BFGoodrich off-road tires are made for rough trails.
2026 GMC Sierra HD AT4 COMFORT 
AT4 INTERIOR
AT4’s Jet Black interior with Kalahari accents features heated and ventilated front seats with leather seating surfaces, and a wrapped heated steering wheel.
POWER FRONT SEATS WITH MASSAGING FEATURE
Experience serious comfort in Sierra HD AT4X’s best-in-class* 16-way power front seats with massaging feature.
PREMIUM ALL-WEATHER FLOOR LINERS
Help protect your interior with available floor liners with removable carpet inserts.
WIRELESS COMPATIBILITY
Connect your compatible smartphone to access a more integrated in-vehicle experience with Apple CarPlay®* or Android Auto™*compatibility.
2026 GMC Sierra HD AT4 SAFETY & WARRANTY 
PRO GRADE PROTECTION
Standard on every new GMC - GMC Pro Grade Protection has you truly protected with features and services including:
- 3-year / 36,000-mile Bumper-to-Bumper Limited Warranty
- 5-year / 60,000-mile Powertrain Limited Warranty
- 5-year / 60,000-mile Roadside Assistance & Courtesy Transportation
- 3-year / 36,000-mile Corrosion Protection
- 6-year / 100,000-mile Rust-Through Protection
- First maintenance visit
FORWARD COLLISION ALERT
Forward Collision Alert can warn you if it detects a potential front-end collision with a vehicle you’re following so you can quickly take action. It can also provide a tailgating alert if you’re following a vehicle much too closely.
FRONT AND REAR PARK ASSIST
Front and Rear Park Assist* can provide distance alerts to nearby detected objects in front of or behind your vehicle to help you park and avoid collisions at low speeds.
LANE CHANGE ALERT WITH SIDE BLIND ZONE ALERT*
Lane Change Alert with Side Blind Zone Alert can provide side-mirror visual alerts when a detected moving vehicle is quickly approaching or is in your side blind zone. It can help you avoid lane change collisions.