SAN DIEGO — GMC is expanding its new AT4 subbrand and many defining characteristics of the Sierra 1500 to its heavy-duty brethren.
Like the light-duty model, the 2020 GMC Sierra 2500HD and 3500HD will feature the brand's six-way MultiPro tailgate, large head-up display and advanced trailering system with an app, among other things.
Compared with the current Sierra HD, the redesigned pickup is taller and longer but features a 1-inch lower bed lift-in height. It incorporates design elements similar to its light-duty sibling, including redesigned C-shaped headlamps and taillamps and a larger grille — unique to each trim — and functional hood scoop.
"It's bigger, stronger and smarter," Duncan Aldred, vice president of GMC, said during the vehicle's Tuesday unveiling. He called the Sierra HD "the crown jewel" of the brand’s lineup.
The pickup, expected to go on sale late summer, will be available in base, SLE, SLT, AT4 and Denali in dual-rear-wheel and single-rear-wheel configurations. Like its Silverado HD sibling, the Sierra HD will be powered by an all-new gasoline engine or Duramax 6.6-liter diesel engine with SAE-certified 445 hp and 910 pound-feet of torque.
The performance of the diesel engine, mated to an Allison-branded 10-speed transmission, is similar in horsepower to similar Ford and Ram models, but with lower torque output. Ford's 6.7-liter Power Stroke V-8 diesel is rated at 450 hp and 935 pound-feet of torque, while the Ram HD's Cummins 6.7-liter diesel engine features 400 hp and 1,000 pound-feet of torque.
More than 90 percent of current Sierra HD buyers purchase crew cab models with diesel engines, according to Aldred.
Towing capacity, according to GMC, will exceed 30,000 pounds. GM did not release pricing or payload for the pickup. Aldred called the pickups “the ultimate trailering machines,” following a Sierra HD 3500 model pulling a large boat and marine lift behind it during the unveiling.
The boat and hoist weighed more than 225,000 pounds. GM said it will release specific towing, payload and other specifications closer to launch.
The Sierra HD AT4 model, like its light-duty siblings, features darker or blacked-out parts as well as additional off-road components such as off-road suspension, Rancho shocks, skid plates and an Eaton locking rear differential.
GMC launched the AT4 subbrand last year on the 2019 Sierra 1500.
GM invested $1.5 billion to support the launch of the redesigned Sierra HD and Silverado HD at Flint Assembly in Flint, Mich.