Captivating Features


Built to power you and your trailer off-road, the Sierra HD AT4 offers towing up to 21,130 lbs.†

GMC 2021 Sierra 3500 HD AT4


The available HD surround vision system provides up to a class-leading, available 15 camera views† and multicolor 15" diagonal Head-Up Display with Off-Road Inclinometer and HD Surround Vision† help drivers stay connected and in command.

GMC 2021 Sierra 3500 HD AT4


Sierra HD AT4’s adventurous exterior appearance comes complete with premium black chrome finishes, modern red details, best-in-class heavy-duty Cargo Bed Volume† and a heap of truck bed enhancements.

GMC 2021 Sierra 3500 HD AT4


The comfortable, expansive cabin features a unique athletic interior with Jet Black with Kalahari accents that gives the Sierra HD AT4 increased durability with the same premium feel.

GMC 2021 Sierra 3500 HD AT4

Baton Rouge, Louisiana

The best place to find your perfect vehicle.

The 2021 GMC Sierra is an absolute beast on the road because of its robust and outstanding features. This car can tow substantial cargo for a long distance, and at the same time, accelerate perfectly because of its potent powertrains. The Sierra 3500HD AT4 will be excellent for drivers located in Baton Rouge, LA, and Louisiana because it is heavy-duty, and it can perform well in rough terrain. We at Royal Buick GMC dealership are committed to giving you details about some of the best features that this car has.

GMC 2021 Sierra 3500 HD AT4

Powerful Presence

The Exterior

This vehicle's exterior design is impressive because it is robust, which clearly shows how powerful it is compared to other cars in its class. This GMC vehicle has some unique trailering mirrors that give the driver of the vehicle HD viewing of the car's rear side, which is very useful, especially when switching lanes on the highway. At its front, it has an air induction system that allows cool air to enter and circulate in the engine.

It is essential as it helps maximize the vehicle's horsepower, which helps boost its overall performance. This vehicle's wheels are also unique because they are of exceptional quality, meaning they have long durability. Its rims are also excellent because they have a unique design, adding to the vehicle's beauty.

GMC 2021 Sierra 3500 HD AT4

The Interior

The Premium Interior

This vehicle's interior was designed to provide the people riding this vehicle outstanding comfortability. For starters, the steering wheel of this car is leather-wrapped, and it also has a heating function to enhance the driver's comfortability when they are behind the wheel. The front seats of this car also have a heating function to enhance comfortability during the cold seasons.

Impressively, the driver seat is slightly elevated to give the driver a good view of the road, which significantly boosts drivers' confidence on the road. The spaces between the seats are also adequate both for legroom and headroom, meaning that taller folks can also be comfortable in this car. Moreover, below the backseat at the back, there is a smart storage space where you can store essential items when you hit the road.

GMC 2021 Sierra 3500 HD AT4

The Innovation

Advanced Technology

Frankly, in this vehicle, you will find some of the latest innovations and incredible technology that is simply on another level. For example, this car has 15 cameras around it that help the driver monitor its surroundings. Besides, they are also helpful when the driver is reversing the car. This car also has a unique infotainment system that keeps you connected to the internet using its 4G Wi-Fi connectivity. It also has an excellent audio system that keeps you entertained when you are on the road.

GMC 2021 Sierra 3500 HD AT4

Powerfully Efficient

The Performance

The performance of this vehicle is excellent, thanks to its engines. This car uses V-8 engines that are exceptional in powering it. The first V-8 engine you can use on this car is a 6.6 liters gasoline engine with a horsepower of 401, and it comes with a direct fuel injection system. The second V-8 engine still has a capacity of 6.6 liters, but it uses turbo diesel. Its horsepower is 445, and it comes with common-rail direct fuel injection. Moreover, this car is also equipped with responsive suspensions that significantly boost its performance.

The suspension system provides the vehicle's wheels with proper alignment, and they also ensure that the car has optimum ride comfort like no other. Furthermore, the car also has an electric parking brake that helps stop the vehicle once it is adequately parked to prevent it from rolling when the parking gear is engaged.

GMC 2021 Sierra 3500 HD AT4

Safety Technologies

The Safety

Primarily, this 2021 GMC Sierra 3500HD AT4 has impressive safety features that make it safe to drive, even for new drivers. Ideally, it has a cruise control feature that helps the driver to maintain a safe distance between other cars on the road. Uniquely, the system can determine the speed of the cars surrounding this Sierra 3500HD, and it ensures that the car is on a safe distance to avoid accidents.

Moreover, it also has a lane departure warning system that helps the driver to maintain their lane and avoid confusion on the road. Ideally, when the GMC Sierra 3500HD driver changes lanes on the road without the proper signals, it is likely to confuse other drivers, leading to fatal accidents.

GMC 2021 Sierra 3500 HD AT4


Uses a brief, gentle steering wheel turn to alert you when you may be unintentionally drifting out of detected lane lines, so you can steer to stay safely in your lane. If needed, you may receive additional Lane Departure Warning alerts. System alerts do not occur if you’re using your turn signal or it detects that you are intentionally leaving your lane. Available on SLE, SLT and AT4. Standard on Denali.

GMC 2021 Sierra 3500 HD AT4


Front and Rear Park Assist provides distance alerts to nearby detected objects to help you park and avoid objects at low speeds. Available on base Sierra HD, SLE, SLT and AT4. Standard on Denali.

GMC 2021 Sierra 3500 HD AT4


Automatic Emergency works with Forward Collision Alert to help you avoid or reduce the severity of a front-end collision with a detected vehicle you are following. This feature works at speeds below 50 MPH. Camera technology is used to automatically provide hard emergency braking or enhance the driver’s hard braking. Available on base Sierra HD, SLE, SLT and AT4. Standard on Denali.

GMC 2021 Sierra 3500 HD AT4


Rear Cross Traffic can alert you to detected left- or right-cross traffic behind you when in Reverse. Available on Sierra HD, SLE, SLT, and AT4. Standard on Denali.

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Explore Sierra 3500 HD AT4

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