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2026 GMC Sierra HD AT4 OVERVIEW

2026 GMC Sierra HD AT4 in Alton

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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

Sierra HD AT4
Sierra HD AT4X

GMC Sierra HD AT4 Dealer in Alton

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.

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$7,500 EV Lease Incentive

0% APR For 36 Months For Well-Qualified Buyers

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2026 GMC Sierra HD AT4 OVERVIEW

2026 GMC Sierra HD AT4 in Alton

2026 GMC Sierra HD AT4 MODELS

Sierra HD AT4

Sierra HD AT4X

GMC Sierra HD AT4 Dealer in Alton

2026 GMC Sierra HD AT4 PERFORMANCE

DURAMAX 6.6L TURBO-DIESEL V8 ENGINE

AT4 OFF-ROAD READINESS

AT4X OFF-ROAD PROWESS

2026 GMC Sierra HD AT4 APPEARANCE

AT4 GRILLE

AT4X EXTERIOR

20" AT4 WHEELS

2026 GMC Sierra HD AT4 COMFORT

AT4 INTERIOR

POWER FRONT SEATS WITH MASSAGING FEATURE

PREMIUM ALL-WEATHER FLOOR LINERS

WIRELESS COMPATIBILITY

2026 GMC Sierra HD AT4 SAFETY & WARRANTY

PRO GRADE PROTECTION

FORWARD COLLISION ALERT

FRONT AND REAR PARK ASSIST

LANE CHANGE ALERT WITH SIDE BLIND ZONE ALERT*

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Disclaimers