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2021 GMC Sierra 2500HD Overview

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2021 GMC Sierra 2500HD driving down a country road
Photo: GMC

The 2021 GMC Sierra 2500HD is a full-size pickup that offers both gas- and diesel-powered options, as well as some unique features like the MultiPro tailgate, class-leading spaciousness, and the off-road-capable AT4 trim level.

It’s available in five trim levels: Sierra, SLE, SLT, AT4, and Denali.

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What’s New

Although the refreshed Sierra was launched back in 2020, the 2021 model boasts a few updates. It now boasts wireless smartphone connectivity, an auto-dimming rearview mirror, and available E85 FlexFuel capability for the gas-powered variant. It also gained three new exterior colors: Ebony Twilight Metallic, Cayenne Red Tintcoat, and Hunter Metallic.


2021 GMC Sierra 2500HD towing a trailer
Photo: GMC

The GMC Sierra 2500HD offers a number of unique and class-leading features. It boasts 12 standard cargo tie downs, a CornerStep rear bumper and best-in-class cargo bed volume. Its standard bed provides 69.5 cubic feet of space, while its long bed offers 83.5 cubic feet of room. For easier access to the cargo bed, you can opt for the six-function MultiPro tailgate, which can also serve as a step, a work bench, or a truck bed extender. The Sierra 2500HD also takes some of the guesswork out of towing with the ProGrade Trailering System. In addition to providing trailer diagnostic checks, it also offers Hitch Guidance with Hitch View, which helps you align your truck with your trailer for easier hitching.


  • 2021 GMC Sierra 2500HD Interiorn
  • 2021 GMC Sierra 2500HD trailering technology

On the inside, the GMC Sierra 2500HD comes standard with the kind of no-frills, practical interior you’d expect from a work truck. It sets itself apart from the competition with best-in-class crew cab front head- and legroom, as well as Bluetooth, Android Auto, and Apple CarPlay connectivity.

Higher trims, such as the Denali, offer luxuries like heated and ventilated front seats, heated rear outboard seats, leather upholstery, rear under-seat storage, and built-in navigation.

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The GMC Sierra 2500HD offers two powertrain options. The standard 6.6-liter gas-powered V8 engine pairs with a six-speed automatic transmission. It delivers 401 horsepower and 464 lb-ft of torque. With this engine, you’ll be able to conventionally tow up to 14,500 pounds, or 16,620 pounds with gooseneck towing.

For even more muscle, opt for the 6.6-liter Duramax Turbo-Diesel V8, which channels 445 horsepower and 910 lb-ft of torque through an Allison 10-speed automatic transmission. Thanks to that power, it can tow up to 18,500 pounds, whether with gooseneck or conventional towing.


When it comes to standard safety technology, the Sierra 2500HD only offers the basics, like airbags, a rear-view camera, StabiliTrak, and teen driver mode. However, you can outfit it with more driver-assist technology, including Lane Change Alert with Side Blind Zone Alert, Front and Rear Park Assist, Forward Collision Alert, Rear Cross-Traffic Alert, and the Safety Alert Seat.

Want to see how you can upgrade your Sierra HD? Check out these newly available packages for the 2022 Sierra 2500 HD.