The front of a black 2021 GMC Sierra HD, one of the popular 2021 GMC diesel trucks, is shown from a low angle.

2021 GMC Diesel Trucks: Updates, Improvements, and Legacy

Amid the uptick in popularity of plug-in hybrids and electric vehicles, there’s still a needed space within the automotive industry for powerful diesel engines to get heavy-duty jobs done in the utility, commercial, construction, and independent trucking scene. Thankfully, GMC has not forgotten about diesel truck drivers for its 2021 models and has even gone as far as to update and improve upon the 2021 GMC diesel trucks, including the Sierra and Canyon.

Canyon & Sierra Diesel Power

It’s quite common knowledge that Chevy’s diesel offerings for their trucks are fairly notable: High torque, good horsepower, and a lot of towing muscle. However, Chevy’s Colorado and Silverado aren’t the only GM trucks that are designed to take advantage of diesel powertrains. GMC also embraces the power of diesel and all of the benefits that come along with these powerful engines.

For 2021, both the GMC Sierra and GMC Canyon will continue to provide the consumer market with high-quality diesel engines. For truck drivers interested in GMC’s offerings, there are solid diesel powertrain options for both vehicles in addition to their multiple standard gasoline-based engines that the pickups have always used.

Major Changes For 2021

The big update to the powertrains for the 2021 GMC diesel trucks line-up is more about the refinement of the powertrain’s capabilities rather than any significant changes to the performance stats in terms of engine functionality. The one standout update to the GMC Sierra is that trucks fitted with the Duramax LM2 turbo-diesel have increased their overall tow rating, allowing the full-sized half-ton diesel to tow up to 9,300 lbs – 200 lbs more than the 9,100 lbs of the 2020 model year.

Trailering enthusiasts who prefer hitching trailers, boats, campers, or more to their pickups will surely embrace the new tow rating. This upgrade was thanks to GM upgrading the quality of various engine bay components, in combination with the 10-speed automatic transmission that refines the driving experience and reduces noise, which helps improve the overall capabilities of the GMC Sierra 1500 in particular.

GMC Canyon’s Diesel Power

A grey 2021 GMC Canyon is driving on a winding mountain road.

The 2021 GMC Canyon remains available alongside GM’s other diesel-powered trucks with a 2.8-liter turbocharged Duramax. The engine isn’t just a swap-out from the petrol-based powertrains, but rather the pickup truck has undergone a number of changes to its entire design to ensure that the suspension, handling, and chassis were all engineered to make the most use of the Duramax diesel engine since the introduction of the powertrain.

The turbocharged four-cylinder puts out up to 181 hp and 369 lb-ft of torque, giving it the ability to trailer up to 7,700 lbs worth of cargo depending on the configuration. If you wanted to make use of the four-wheel drive configuration but keep with the torque and benefits of the diesel, you’ll find that possible, too. The four-wheel drive Extended Cab version even affords GMC Canyon drivers with the same 7,700 lbs max trailering rating, with the Crew Cab versions only dropping the rating by 100 lbs to 7,600 lbs.

Much of the heavy lifting of torque transfer can also be attributed to the variable-geometry turbocharger, which directs exhaust flow through specially designed variable vanes to accelerate the turbine blades. This, in turn, increases the passage of airflow and helps to ensure that the torque isn’t wasted when working in conjunction with the six-speed automatic transmission.

The transmission itself is designed to not only maximize the output of torque but also to keep the vehicle running as quiet as possible thanks to the centrifugal pendulum vibration absorbing dampener, also known as a CPVA. This helps to reduce torsional vibrations when a lot of torque transfer makes its way from the engine through the transmission and out through the driveshaft. The reduction in vibrations, in turn, helps to reduce the overall noise generated by the diesel engine and provides a smoother overall driving experience.

GMC Sierra’s History With Duramax

The GMC Sierra has been around a lot longer than most other GM trucks. In fact, it predates the Chevy Silverado by an entire generation. It should come as no surprise that the GMC Sierra has been furnished with a Duramax turbocharged diesel engine since the second generation. Unlike the GMC Canyon, which is a light-duty pickup, the GMC Sierra offers truck drivers diesel configurations for both half-ton and heavy-duty pickups with the 2500 and 3500 HD series.

Since the release of the fourth generation in 2019, the GMC Sierra 1500 has joined its diesel-powered heavy-duty siblings in offering a Duramax turbo-diesel under its hood. This is a 3.0-liter 277 hp engine that produces up to 460 lb-ft of torque. This means that the Sierra 1500, when matched with a diesel, is convenient both for off-road activity and for towing or trailering.

Much like the smaller GMC Canyon, the GMC Sierra features a variable geometry turbocharger to help with airflow efficiency, as well as an active thermal management system for improved engine temperature control and improved performance. The ceramic glow plugs help with cold starts, heating up the engine quickly and getting the vehicle moving right out of the gate during extremely cold weather.

As mentioned above, the 2021 GMC Sierra is capable of impressive towing feats when paired with the 3.0-liter Duramax I6 turbo-diesel and has a maximum trailering capacity of up to 9,300 lbs depending on the configuration. The Sierra 2500 HD is capable of much larger towing feats thanks to being offered with an optional 6.6-liter Duramax V8, which boosts the towing capacity to 18,510 lbs. The numbers get even higher with the Sierra 3500 HD, where the Duramax turbo-diesel can muster an impressive tow rating of up to 36,000 lbs.

A grey 2021 GMC Sierra 1500 is towing a boat past trees.

More Diesel Means Better Fuel Economy

An interesting development with the 2021 GMC diesel trucks is that with increased towing capabilities, the trucks have not lost their fuel economy ratings. Usually, with engine changes, there tend to be trade-offs, but that wasn’t the case with the Canyon or Sierra. Both of these trucks maintain their fuel economy ratings, with both the 2021 Sierra 1500 diesel and the 2021 Canyon diesel offering incredible city and highway mileage.

These advancements in maintaining high power output with better gas mileage are part of what makes GMC’s diesel line-up quite an attractive option for 2021 models. The GMC Canyon manages a fuel economy of 20 MPG in the city and 30 MPG on the highway with the two-wheel drive configuration, and 19 MPG in the city and 28 MPG on the highway with the four-wheel drive configuration.

The 2021 GMC Sierra’s diesel engine manages a maximum of 23 MPG in the city, and 33 MPG on the highway with a two-wheel drive configuration, and 22 MPG in the city and up to 26 MPG on the highway with a four-wheel drive configuration.

Over time, GMC has consistently managed to improve nearly every aspect of its pickup trucks, whether in the light-duty or the heavy-duty category, without sacrificing the durability, functionality, or efficiency of the trucks. With noise reduction and lower vibrations for the newer GMC diesel trucks, combined with improved trailering, and great fuel economy, it seems like a great time to explore the Canyon or Sierra as potential options if you’re looking for a solid pickup with great diesel performance.