The 2020 GMC Sierra HD is meant for work. It tows, it hauls, it carries passengers and cargo from one destination to the other, and it does it with a combination of brutish strength and upscale luxury. Redesigned for 2020, the Sierra HD is bigger than ever, more opulent than ever, and can haul more than ever. It also offers a series of cameras and technology tools that ease the worry of towing. We rate it a 6.8 overall for its class-leading capability, relative comfort, and many useful tech features. (Read more about how we rate cars.)
GMC’s customers told the brand they wanted a bigger, more work-oriented truck, so that’s just what GMC provided for 2020. The new Sierra HD is considerably larger than the already monstrous truck it replaces, and it offers up to 52 percent more towing capacity, which now tops out at 35,500 pounds.
The look is similar to the light-duty, 1500-series trucks, but also different. The face of the truck is much taller and more cohesive than that of the related Chevy HD trucks. The bed sides are shorter and side steps are provided in front of the rear wheels to make bed access easier.
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GMC offers a choice of two engines, a new 6.6-liter, 401-horsepower gas V-8 that replaces a 6.2, and the carry-over Duramax 6.6-liter turbodiesel that grinds out 445 hp and 910 pound-feet of torque. The Duramax is hooked to a new 10-speed automatic Allison transmission that replaces a 6-speed, and a new four-wheel-drive system offers a full-time 4-High Auto setting for the first time in the Sierra HD.
Both engines are strong, but the diesel is the choice for towing, and the new 10-speed automatic helps take advantage of its power by keeping the revs in the power band more often. GMC offers up to 15 camera views to further improve towing. Otherwise, the GMC’s road manners are predictably ponderous given its size, but the ride is smoother than the competition due to an independent front suspension.
Inside, the 2020 GMC Sierra HD has room for a king in each seating position, especially in the crew cab, and its materials are upscale though not as luxurious as those in the Ram HD. The AT4 and Denali sit at the top of the lineup and offer amenities such as leather upholstery, heated and cooled front seats, heated rear seats, a heated steering wheel, OnStar telematics with a 4G LTE wi-fi hotspot, an 8.0-inch screen for infotainment with Apple CarPlay and Android Auto connectivity, a Bose audio system, and wireless device charging.
The 2020 GMC Sierra HD offers some important safety features, too. It can be ordered with front and rear park assist, GM’s rear camera mirror, blind-spot monitors, rear cross-traffic alerts, forward collision warnings with automatic emergency braking, and lane departure warnings.