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Exterior view of the 2020 GMC GMC Sierra 2500 Denali

If you've been putting off buying a new heavy-duty truck because you've been "waiting for the new ones to come out," I have great news for you. They're already here. It doesn't matter which brand you prefer.

RAM came out with an all-new 2500 and 3500 for the 2019 model year. Ford thoroughly revised and updated its Super Duty trucks for 2020. The 2020 versions of Chevrolet's Silverado HD pickups are all-new. Chevy's corporate cousin GMC totally overhauled its Sierra HD lineup, making it more distinctive, advanced, and capable than ever. I got the opportunity to experience one of GMC's newest workhorses when it sent me a 2020 Sierra 2500 HD Denali to test for a week.

2020 GMC Sierra 2500 Denali Exterior

Exterior view of the 2020 GMC GMC Sierra 2500 Denali

Ford, RAM, and General Motors built their heavy-duty trucks to do the same things, but when it comes to styling, they went in wildly different directions. Ford's Super Dutys have a square-jawed, chiseled look to them. RAM's pickups have softer, more classic lines. Chevy and GMC went big and bold. Their new designs have been polarizing, but I honestly liked the looks of my Sierra test truck. It made me think of a building - and not just because it was nearly 21 feet long, almost seven feet wide (excluding its mirrors), and close to just as tall. I credit its color and trim work. With its Dark Sky Metallic premium paint and abundance of chrome, it made me think of a high-rise in a metropolis designed by an architect who wanted their creation to be a distinguishing mark of their city's skyline.

GMC built a lot of function into that immediately recognizable form. The wide vent on the bulging hood joined forces with the massive grille to feed dense, cool air to the Denali's engine. The giant trailer mirrors could power fold and extend to provide a better view of a trailer behind the Denali. A pair of chrome assist steps helped make getting in and out of the cabin easier and more dignified.

My press loaner had the regular 6'9" cargo box. In stock form, that comes with a spray-on bed liner, LED lighting, and GMC's versatile MultiPro Tailgate, which could serve as a regular tailgate, a two-level load stop, an assist step, and more. GMC added an optional 5th wheel/gooseneck prep package with capped holes in the bed floor and a seven-pin trailer harness to make the bed even more helpful.

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2020 GMC Sierra 2500 Denali Interior

Interior view of the 2020 GMC GMC Sierra 2500 Denali

My girlfriend Eli's birthday fell around the middle of my week with the Denali. To celebrate, the two of us and her cousin Bethany and her boyfriend Logan went to the Austin City Limits Music Festival. While others took Ubers and Lyfts, we rode in style to the parking garage closest to Austin's Zilker Park (the catch was we had to go around and park on the open top level because the Denali wouldn't fit through the entrance to the garage). GMC dressed the cabin in Jet Black leather and accented it with ash wood and brushed aluminum trim. Up front, Eli and I had 10-way power seats with heating and ventilation. Bethany's and Logan's outboard seats in the back were heated as well, but the summer heat and humidity rendered that function more than redundant. Luckily, they had their own pair of HVAC vents and I kept the AC cranked.

As the flagship model in the Sierra HD range, my Denali tester had GMC's top-of-the-line infotainment system: an eight-inch high-definition touchscreen with Apple CarPlay/Android Auto compatibility and navigation. The Denali Ultimate Package upped the Denali's level of luxury by adding a power sunroof in addition to a variety of safety features (more on those further down).

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2020 GMC Sierra 2500 Denali Powertrain

Engine view of the 2020 GMC GMC Sierra 2500 Denali

The 2020 Sierra HD is available with two 6.6-liter V8 engines. The gas model routes its 401 horsepower and 464 lb-ft of torque through a six-speed automatic transmission. GMC equipped my Denali media special with the Duramax diesel engine. That generates 445 horsepower and 910 lb-ft of torque and is mated to a 10-speed Allison automatic.

My particular test truck had a Gross Vehicle Weight Rating (GVWR) of 11,350 pounds. With its 3.42:1 rear axle ratio, it was capable of hauling 3,563 pounds of payload and towing 18,500 pounds, whether with a conventional hitch or a 5th wheel/gooseneck setup.

To keep all of that weight in check, the Sierra 2500 HD Denali has a trailer brake controller and GMC's ProGrade Trailering System with 15 camera views that show the truck, bed, rear hitch, and any attached trailer from a multitude of informative angles.

The timing of my media loan didn't allow me to haul or tow anything with the Denali. However, driving the truck unladen gave me a great idea of its general dynamics - and an appreciation for them. Throttle response and acceleration was surprisingly snappy for such a huge diesel-powered truck. Most large four-wheel-drive rigs have hopelessly slow and vague steering, but the Denali's rack, which incorporated GMC's Digital Variable Steering Assist tech, provided a satisfying amount of feel and directness.

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2020 GMC Sierra 2500 Denali Safety

View of safety equipment of the 2020 GMC GMC Sierra 2500 Denali

My test truck had an impressive list of safety features as basic equipment. Driver Alert Package I contained a front and rear parking assistance system and Lane Change Alert with Side Blind Zone Alert. There was even more in Driver Alert Package II, including Forward Collision Alert, Lane Departure Warning, and Automatic Emergency Braking.

As I mentioned earlier, the Denali Ultimate Package was full of safety features. The Rear Camera Mirror provided a headrest- and bodywork-free view of everything behind the Denali. HD Surround Vision gave me low-speed views of everything around the truck. The Bed View Camera was just what it sounds like.

By far, the standout feature of the Denali Ultimate Package was the 15-inch head-up display that enabled me to see my speed, directions from the navigation system, and more without taking my eyes off of the road.

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2020 GMC Sierra 2500 Denali Overall

View of the exterior of the 2020 GMC GMC Sierra 2500 Denali

Every heavy-duty truck on the market right now has either been significantly updated or completely re-designed and re-engineered since the 2019 model year. If you're looking to trade in your current pickup for one that's Professional Grade, go to your closest AutoNation GMC dealership and test-drive a 2020 Sierra 2500 HD Denali. Prices start at $63,700*; one loaded up just like the one you see here will have a sticker price of $78,455.

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Derek Shiekhi | Apr 02, 2020

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2020 GMC Sierra 2500 Denali Specs


4-door, 5-passenger, 4x4 pickup


6.6L V-8

445 hp / 910 lb-ft

10-speed Allison automatic


15/20 mpg (city/hwy)

NHTSA Safety Rating

Not available

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*MSRP excludes tax, license, registration, destination charge and options. Dealer prices may vary.

**Based on EPA mileage ratings. Your mileage will vary depending on specific vehicle trim, how you drive and maintain your vehicle, driving conditions, and other factors.