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The 2020 GMC Sierra introduces a 3.0-litre Duramax diesel engine to its lineup.


Small-displacement diesel engines have had enough recent lows, it might come as a surprise that a major automaker is willing to gamble on developing a new one and bringing it to market.

GMC, however, is proving with its new 3.0-litre Duramax diesel that it’s not afraid to rush in where wise emissions angels fear to tread. Of the new features in the light duty 2020 Sierra 1500 pickup truck, the new engine is the highlight.

And for good reason. For all the bad blood created by Volkswagen’s diesel-emissions scandal, it is beyond debate that small diesels done right can deliver more pulling power, longer engine life and substantially better fuel economy than gasoline equivalents. And, importantly, they can do it all without either filling the air with noxious fumes or noisy clatter.

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GMC went back to the drawing board on this engine, says John Barta, the engine’s assistant chief engineer. It started with a “clean sheet” to make a diesel that would be relatively light, fuel-efficient and well-suited to its 1500 line of light-duty half-ton pickup trucks. It’s one of the reasons why GMC chose an inline six-cylinder configuration rather than the V-6 that has become ubiquitous in the industry.

Barta says an inline six offers significant weight savings over a V-6 because it reduces duplication of parts. It needs one camshaft instead of two and just one set of timing chains, and eliminates the need for the balance shafts required in a V configuration.

“We wanted great fuel efficiency and (minimal) greenhouse impact,” said Barta. “The design is absolutely spot-on for this application.”

The AT4 trim turns the Sierra into an off-road warrior.

Darcy Bacha

GMC also worked very closely with regulators, including the U.S. Environmental Protection Agency (EPA) and the California Air Resources Board (CARB), to ensure the diesel would be fully compliant right out of the gate, Barta said, and it was also vetted by Transport Canada. (Fiat Chrysler was not so lucky with its 3.0 EcoDiesel, introduced on Ram trucks in 2014. It had to recall and fix its engines and pay owners US$2,800 per vehicle for failing to meet EPA standards.)

“The rules are very stringent,” said Barta. “There’s absolutely no ambiguity on the testing.”

The result can be felt behind the wheel during a recent media event in Jackson Hole, Wyo. The diesel hits its maximum torque – essentially pulling power – of 460 the very low revs of 1,500 rpm and stays pretty much at that level right up to nearly 3,100 rpm. A new 10-speed automatic ensures the engine remains at optimum pulling power no matter how slow or fast you drive.

Capacity in the truck's cargo bed is rated at 830 kilograms.

Doug Firby

The truck can pull a mid-size trailer of up to 4,127 kilograms or carry up to 830 kilograms of cargo in the box with very little fuss. And the truck has none of the notorious rattle and vibration that diesel engines were once known for.

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The light duty Sierra is essentially the same redesigned vehicle introduced for the 2019 model year, so the appearance and basic architecture are unchanged. That includes the nifty MultiPro tailgate, which has six configurations to ease access and even spark up the tailgate party, thanks to optional built-in speakers. Other upgrades include a multicolour head-up display; a rear-camera mirror option; and GMC’s ProGrade trailering safety and convenience technology, carried over from 2019.

The new Sierras keep the MultiPro tailgate introduced for the 2019 model year.

The best new option, however, is the carbon-fibre cargo box, which GMC calls CarbonPro (promised in 2019, but not widely available until now). Cargo boxes can quickly look well-aged, especially if you throw tools, lumber supplies or firewood into the back. Not so with this box, made of a light and super-tough material used in Formula 1 racing cars. Journalists were encouraged to drop chainsaws, concrete blocks and anchors into the box. Except for a few scratches, it was unharmed. Remarkably, it is also 28 kilograms lighter than a conventional steel box.

A tossed concrete block left only minor scratches on the carbon-fibre cargo box.

Doug Firby/The Globe and Mail

GMC featured its three premium models at the 2020 truck unveiling – the dressy Denali, the off-road-ready AT4 and the monochromatic Elevation. For buyers on a tighter budget, however, the company is making the diesel available on the cheaper SLE and SLT models. Only the basic work truck is denied the diesel.

(No such luck on the CarbonPro box, however. It is only offered on higher trim levels.)

As with the other two Detroit-based automakers, GM has spent massive sums developing its trucks in recent years. It’s not surprising, considering the segment is worth US$65-billion in annual revenue, according to the company.

The results are trucks that defy old stereotypes of being noisy, rough and wasteful. The capable and fuel-efficient Sierra 1500 is a shining example of how far they have come.

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The 2020 Sierras are to be available in dealerships this fall.

The writer was a guest of the automaker. Content was not subject to approval.

Tech specs

  • Base price/As tested: $50,448 (SLE model 2WD Double Cab Short box)/$76,343 (AT4 model with 4WD Crew Cab)
  • Engines: Gasoline: 2.7-litre turbo, 4.3-litre V-6, 5.3-litre V-8, 6.2-litre V-8. Diesel: 3.0-litre I6
  • Transmission/drive: Six-, eight- or 10-speed automatic, depending on engine (gas); 10-automatic (diesel). Four-wheel drive is an option.
  • Fuel economy (litres/100 km): With 5.3-litre V-8 gasoline engine: 15.3 city/11.2 highway. (The U.S. EPA estimates the diesel at 10.2 city/7.1 highway.)
  • Alternatives: Ram 1500, Ford F-150, Nissan Titan, Toyota Tundra


Simple and clean, the light-duty Sierra has a distinctive grill that sets it apart from its cousin, the Chevrolet Silverado. It’s not quite as boss-looking as the Ford F-150, but a significant leap forward from previous Sierras.


Premium interior finishes help create a car-like experience.

The addition of sound insulation under the hood has helped reduce cabin noise. Interior finishes in the premium models reflect the trend toward car-like experiences. The instrumentation cluster is reasonably intuitive.


The AT4's all-terrain Goodyear Wrangler DuraTrac tires help it tackle rough terrain.

Darcy Bacha

The new 3.0-litre diesel strikes the right balance between solid fuel economy and working power. Adaptive ride-control ensures the truck remains comfortable for passengers, even when carrying heavy loads. Brakes have been beefed up, too. The AT4 package turns the truck into a legitimate off-roader. It includes five-centimetre suspension lift, standard 4WD with a two-speed transfer case, locking rear differential, skid plates, Rancho monotube shocks and 18-inch wheels with all-terrain Goodyear Wrangler DuraTrac tires.

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Available enhancements include a high-definition rear-vision camera (in addition to a standard rear-view mirror), lane-change alert, blind-spot alert and surround vision. The infotainment system comes in 18- and 20-centimetre diagonal screens, and includes Apple CarPlay and Android Auto compatibility.


Cargo-box sizes range from the 5-foot 8-inch “short” box to a full 8-foot box in regular cab models.

The verdict: 8.5

The 2019 redesign of GMC’s light duty pickups produced a solid vehicle for work and play, and the addition of the 3.0-litre diesel in the 2020 version only makes things better. A lot of its highly desirable tech and convenience features, however, are only available in premium models.

Darcy Bacha

The writer was a guest of the automaker. Content was not subject to approval.

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