GMC's Sierra Heavy Duty debuts with all the goodies

Nora Naughton
The Detroit News

San Diego — GMC's redesigned 2020 Sierra Heavy Duty pickups and an all-new AT4 version debuted here Tuesday — with boats in tow.

GMC's behemoth Sierra 2500 and 3500 are getting an upgrade less than a year after the brand redesigned the flagship Sierra 1500 light-duty pickup.

Borrowing from that redesign, GMC's 2020 Sierra Heavy Duty can be equipped with the MultiPro six-function tailgate, rear-camera mirror and ProGrade Trailering system — all of which debuted on the Sierra 1500 last year.

The new heavy-duty models borrow design cues from their smaller siblings, including the C-shaped LED daytime running lamps that create GMC's front lighting signature known as the "light blade."

The 2020 GMC Sierra 2500 HD SLT

GMC also is expanding the new AT4 off-roading brand that debuted on the light-duty pickup with an all-new Sierra AT4 Heavy Duty available in crew-cab configurations as both a 2500 and 3500 single rear-wheel offering.

"Sierra is our core," said Duncan Aldred, vice president of GMC. "Making the launch of the all-new model is incredibly important and incredibly exciting." 

Standing taller and longer than the previous-generation Sierra Heavy Duty, the 2020 model is available with a 445-horsepower, 6.6-liter Duramax turbo-diesel developing 910 pound-feet of torque. It's paired with an all-new 10-speed Allison automatic transmission. Together, the bigger frame and stronger powertrain are expected to deliver more than 30,000 pounds of towing capacity.

Details about a new gas engine will come later.


The new Sierra Denali HD dually foreshadowed that the towing capacity could be well in excess of 30,000 pounds when it debuted Tuesday, pulling an 80-foot yacht totaling 225,000 pounds with the help of a fifth-wheel hitch.

Inside, GMC has redesigned the interior to offer more head- and legroom and a higher seating position for drivers to see over a taller hood-line. A larger grille and functional hood scoop feed a cooling system for the  turbo-diesel.

There are also some interior exclusives in the high-end Denali trim — which GMC says makes up more than half of current heavy-duty sales — including leather seats, open-pore wood accents and dark-finish aluminum trim.

On the new light-duty Sierra, the Denali trim makes up 54 percent of sales, while the AT4 accounts for 20 percent.

GMC Pressroom - United States - Videos

The AT4 Heavy Duty package will have some upgrades of its own, including dark-chrome exterior finishes and a grille-surround finished in body color. Inside, the AT4 carries dark and textured aluminum finishes on the steering wheel, center stack and sill plates. The black interior is complemented by Kalahari-brown color accents in the seats and stitching, with embroidered AT4 badging on the headrests.

Following in the light-duty AT4's tracks, the Sierra AT4 Heavy Duty is equipped with an off-road suspension, Rancho shocks, skid plates and Eaton locking rear-differential. The off-road truck rides on standard 18-inch wheels with Michelin all-terrain tires, with an option to upgrade to 20-inch wheels.

The 2020 Sierra HD will compete with Ford Motor Co.'s Super Duty F-250 and F-350 and Fiat Chrysler Automobiles' all-new Ram 2500 and 3500 Heavy Duty, which debuted last week at the Detroit auto show. Ram infused its big new trucks with new technology and luxury in an attempt to gain on GM and Ford in the truck market.

Going on sale in late summer this year, the 2020 Sierra Heavy Duty will be built at Flint Assembly, along with the new heavy-duty Chevrolet trucks, of which GM gave a sneak peek late last year.

Twitter: @NoraNaughton