2021 GMC Sierra 3500HD Review: The Big Kahuna

In the vanguard of heavy-duty pickup truck titans, the 2021 GMC Sierra 3500HD may not be the paragon amongst its vehement rivals but with its authoritarian presence, potent powertrains, and near-unassailable dependability, it's the big kahuna of GMC's Sierra line and a very worthy vehicle in the classification. Rumbling beneath the Sierra 3500HD's hulking hood is a 6.6-liter V8 engine that musters 401 horsepower and 464 lb-ft of torque. However, GMC offers an even mightier Duramax turbodiesel V8 as an option for those who are really serious about hauling. The automaker has been continuously improving the fourth-generation Sierra 3500HD pickup, with this year's model receiving some nifty trailer-assistance technology and additional safety systems. There are, however, still a few flaws that hurt the Sierra 3500HD's chances against the likes of the RAM 3500, Ford F-350 Super Duty, and the Chevrolet Silverado 3500HD.

Sierra 3500HD Exterior

Dimensions

Sierra 3500HD Performance

Engine and Transmission

The source of the 2021 Sierra 3500HD's prodigious power is a 6.6-liter V8 gasoline engine that's been modulated for 401 hp and 464 lb-ft. A 6-speed automatic transmission is appointed to manage outputs and does so to either a rear-wheel drive or all-wheel drivetrain depending on the config chosen. GMC offers the Sierra 3500HD with a 6.6-liter Duramax turbodiesel 8-cylinder unit that generates massive outputs of up to 445 hp and 910 lb-ft for those serious about towing. It comes paired with a polished 10-speed automatic transmission. General performance, payload, and towing capacities depend on the powertrain and body configurations chosen, but the Regular 4-door Cab Heavy-Duty Diesel with the RWD setup and gooseneck hitch will tow a maximum of 36,000 lbs.

Sierra 3500HD Interior

Sierra 3500HD Trunk and Cargo Space

Warranty

Verdict: Is the 2021 GMC Sierra 3500HD A Good Truck?

The 2021 GMC Sierra 3500HD is most certainly a highly proficient and exceedingly dependable workhorse, but it does have quite a few drawbacks that hinder its standing alongside the competition. Its authoritarian aesthetic may be polarizing for some, but its sharp and bulky lines and its over-the-top ruggedness in a selling point for many. Unfortunately, no matter your taste, the Sierra's interior just feels cheap when compared to the interiors of its main competitors, particularly the Silverado's. The premium, heavy-duty pickup truck segment is an extremely competitive one, and automakers are going above and beyond to cram their offerings full of value. But GMC has fallen short on the cabin-quality side of things and, worse, the NHTSA and the IIHS's safety review of the 2021 GMC Sierra 3500HD proved substandard.

Nevertheless, both its V8-equipped powertrains are phenomenal and accord the Sierra 3500HD with some seriously substantial payload and towing capabilities. As with all pickups in this class, however, it chugs fuel like an avid gamer chugs energy drinks. It's also been rated as one of the most dependable heavy-duty trucks money can buy, so you know it will stand the test of time and never let you down.

What GMC Sierra 3500HD Model Should I Buy?

With so many powertrain, cab, and cargo bed configurations, let alone trims, available for the Sierra 3500HD truck, the decision you make will inevitably come down to what you'll need it for. The starting price of the 2021 GMC Sierra 3500HD pickup truck comes in at $37,400 for the US market, which is relatively standard for these cars. If you're a simple admirer of pickup trucks in general and want the best-of-the-best from the GMC Sierra line, then the top-spec Denali is the way to go along with the Duramax turbodiesel engine, 4WD setup with the dual-rear wheels, and extended cargo bed.