Until the GMC Hummer EV makes its debut in the fall, the 2020 GMC Sierra Denali Heavy Duty pickup truck totes the truckmaker’s banner as a flagship. It’s suited to the task.
Up to three tons of anything can be heaved into its boxy rear bed, or it can tow up to 15 tons—roughly equivalent to the weighty expectations ahead for General Motors’ luxury truck division. The Sierra HD dominates attention wherever it goes by dominating a parking lot. That, and an acre of the Sierra HD’s shiny chrome grille has that effect on people.
Flagship? Sure. Battleship? You betcha.
2020 GMC Sierra 3500 Denali
2020 GMC Sierra 3500 Denali
2020 GMC Sierra 3500 Denali
Like the mechanically related 2020 Chevrolet Silverado Heavy Duty, the GMC HD was extensively overhauled for 2020, a mighty undertaking that changed nearly every body panel on the truck except the roof, which is perched six-and-a-half feet off the ground, by the way. GMC estimates that roughly half (or slightly more) truck buyers will opt for the imposing Denali versions that are slathered in chrome, blanketed in leather inside, and mostly armed with a 6.6-liter turbodiesel that chugs fuel almost as prolifically as it lugs.
Almost impossibly, the Sierra Heavy Duty casts a bigger shadow than before. In certain configurations, it’s nearly a foot longer than before, and my 2020 GMC Sierra 3500 dual-rear-wheel pickup spanned more than 22 feet from stem to stern. Walking from hood to tailgate is more than just a mosey; it’s nearly a first down. Navigating the Colorado-class battleship around the streets of Denver was a daunting challenge.
2020 GMC Sierra 3500 Denali
To that end, for 2020 GMC fitted a handful of improvements aimed at drivability. The most noteworthy is an upgraded Allison 10-speed automatic transmission on diesel trucks that replaced a 6-speed box from last year. (Gas models carry on with the 6-speed for this year.)
The 10-speed is a smooth customer, pulling confidently at launch, and sifting through available cogs without a hiccup up or down. There are three overdrive gears to help mitigate the thirst from the 445-horsepower turbodiesel V-8 planted between the 3500’s squared shoulders. Around town, the 3500 barely touches the low-teens for fuel economy with a light foot—single digits are more common—but on highway slogs the truck’s mileage improves closer to the mid-teens. Unladen, of course. (Heavy-duty trucks aren’t required to report fuel-economy estimates to the EPA, despite increasing popularity as family trucks.)
2020 GMC Sierra 3500 Denali
Load up the Sierra HD with a trailer and GMC’s other improvements for 2020 come into view—about 15 of them actually. With more camera angles to broadcast than “Monday Night Football,” the Sierra HD’s focus on long hauling with ease speaks to its mission. Like most heavy-duty trucks, the Sierra HD’s best life is with a trailer attached.
Leaving the horse trailer at home? OK. Without extracurriculars attached the Sierra 3500, the big pickup rides firmly, especially at the rear. GMC uses an independent front suspension for its heavy-duty trucks, which four-wheel-drive competitors from Ford and Ram skip. The big Sierra tucks into parking spaces with reasonable finesse for its size like a linebacker en pointe, but the recirculating ball steering and enormagantic four-ton mass still makes it a ponderous handling vehicle compared to everything else on the road.
2020 GMC Sierra 3500 Denali
Focused intently on the road from behind the wheel might be the best view of the Sierra 3500 anyway. Compared to the Ram HD and updated Ford Super Duty, the GMC’s interior isn’t as richly appointed or convenient as the others; disappointing for a truck that costs north of $ 80,000. There are a few perks: a bright head-up display projects more than 15 inches of information across the windshield, and small in-seat storage compartments help hide pricey work equipment or valuables.
Cruising is mostly a quiet affair, even while the 3500 chugs up Interstate 70 toward the Rockies. It barely intrudes on conversation, and the 10-speed has all the right answers for 5% grades up or down. More so than any other vehicle on the road, the Sierra HD’s seating position is up high—eye level with some semi-tractor trailers, even—that gives drivers good outward vision, even if it’s at the cost of what’s lurking perilously close to the wall of grille up front.
2020 GMC Sierra 3500 Denali
GMC’s origami tailgate is a boon, too. The tailgate drops a small center section, folds down the whole gate, unfurls a stair, raises a grab bar, makes your lunch—one of those things is made up, but it’s all very useful. Provided you can figure out the right combination of buttons to press, levers to pull, or steps to deploy to get the right thing to open, it makes stepping into the tall bed much easier. (Beware of using the deployable steps with certain types of trailer hitches, however. The tailgate can bang against those.)
The 2020 Sierra HD Denali is a fine flagship now for GMC, whose future looks bright with electrified trucks and suburban luxobarges. It’s bright even though the Sierra HD is nearly big enough to block the sun.
