GMC unveils 2020 Sierra HD pickups with new 10-speed transmission

Updated May 4, 2019
2020 Sierra 2500HD2020 Sierra 2500HD

Following the December reveal of the redesigned Chevrolet 2500HD and 3500HD, General Motors is taking the wraps off of the rest of its 2020 heavy duty lineup with the introduction of its new GMC Sierra HD models. 

Though most of the new features GMC is touting on these new pickups have to do with towing, there are a couple other notable differences between these and the 2019 Sierra HD models.

First, the 2020 Sierra HD trucks mark the introduction of an all-new 10-speed automatic transmission from Allison. GM says this is the first 10-speed to be offered in the HD segment, noting that the closer gear spacing allows the engine to operate in an optimal range at all times, through varying load and terrain conditions.

The 10-speed gearbox will be paired to the 6.6-liter Duramax introduced in 2016. The powertrain is rated at 445 horsepower and 910 lb.ft. of torque.

Second, like the new Chevy HD models, the 2020 Sierra HD trucks feature a new design that incorporates a taller hood line and roof along with a longer wheelbase.

2020 GMC Sierra 2500HD Denali2020 GMC Sierra 2500HD Denali

The grille on these new trucks is larger as well, featuring the functional hood scoop introduced on last year’s HD models.

With the larger design, GMC says the 2020 Sierra HD Crew Cab models will have best-in-class front headroom and legroom. To get your eyes over that taller hood, the seating has also been raised.

The Denali model of these trucks will feature exclusive interior details like premium leather seating, wood trim, and dark-finish aluminum decor.

2020 GMC Sierra 2500HD Denali2020 GMC Sierra 2500HD Denali

Despite the larger dimensions, GMC has actually lowered the bed lift-in height by 1 inch for easer loading and fifth-wheel/gooseneck trailering. The bed also features cargo side steps on all box styles located in front of the rear wheel openings that complement the integrated corner steps in the rear bumper.

Also retained from last year’s Sierra HD models is the six-function MultiPro tailgate that comes standard on the SLT and Denali models.


Towing features

Tailgate of the GMC Sierra Denali heavy duty truckWith the new transmission and larger frame, GMC says its 2020 HD models will deliver “dramatically greater towing capacity than previous models, well in excess of 30,000 pounds.” Complete details on towing and hauling will be announced at a later date, GMC says.

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To complement the added towing capability, GMC will offer its ProGrade Trailering System on these trucks, bringing up to 15 unique camera views to the center console, including a transparent trailer view to provide a better view around what’s in tow. The system constructs this transparent view by stitching together images captured by cameras mounted on both the tailgate and on the rear of the trailer.

Sidestep for GMC Sierra

The system also includes an in-truck trailering app with with a trailer light test, trailer electrical diagnostic, trailer tire pressure and temperature monitoring, pre-maintenance reminders and a departure checklist.

The following trailering features are also available:

  • Auto Electric Park Brake to automatically apply the parking brake to help maintain truck position when hitching.
  • All-new Park Grade Hold Assist enhances hill hold by using braking effort at each wheel for an extended period of time.
  • All-new larger, door-mounted trailering mirrors with a four-bar link providing power extend and retract for the driver and passenger sides.
  • Integrated trailer brake controller that works with the trailer profile in the Trailering App to recall a specified trailer’s most recent gain setting.
  • Tow/Haul mode that remains engaged on the next key-on cycle, for up to four hours; includes a reminder the feature is engaged.
  • Hill Start Assist and Hill Descent Control.
  • Trailer Sway Control.
  • Auto Grade Braking and Diesel Exhaust Braking.
  • Digital Variable Steering Assist that dynamically optimizes power steering according to driving scenarios, including trailering, and enables features like road pull compensation.
  • Trailering Info Label placed on the driver’s door jamb that clearly calls out the truck’s specific trailering information, including curb weight, GVWR, GCWR, maximum payload, maximum tongue weight and rear GAWR.8

GMC is also making several in-trailer functions accessible through its myGMC smartphone app. Billing these as similar to “smart home” features, the app will allow drivers to control things like a trailer’s air conditioning or water heater, check water and holding tank levels or monitor fuel levels on trailers equipped with generators.

To make use of those features, the trailer needs to be equipped with an iN∙Command control system from ASA Electronics, GMC says.

The 2020 Sierra 2500HD and 3500HD will go on sale later this year in dual rear wheel and single rear wheel configurations. Pricing will be announced closer to launch.

GMC Sierra headlight

GMC Sierra Denali hubcap

Interior of GMC Sierra Denali

Center console of GMC Sierra Denali 2500 heavy duty truck