The GMC Sierra HD and Chevy Silverado HD

CALGARY, Alta. — Pulling power is more than just a source of pride among owners of heavy-duty pickup trucks. These trucks usually have a job to do and that job normally entails hauling and towing some serious payload.

That’s why when GM redesigned its GMC Sierra and Chevy Silverado, it was particularly attentive to the towing and hauling requirements of its heavy-duty customers. About 20% of all full-sized pickups sold in Canada are of the heavy-duty variety, which in 2013 represented about 62,000 trucks. The new-look 2015 Sierra HD and Silverado HD will begin hitting dealer lots shortly and they’ll be greeted enthusiastically by customers looking for both a rugged and luxurious work truck.

GM recently made a small fleet of 2015 Sierra HD and Silverado HD trucks available to truck and automotive journalists for a two-day drive through scenic Southern Alberta. Along the way, we visited historical sites such as Head Smashed In Buffalo Jump, Bar U Ranch and Waterton Lakes Provincial Park.

But the most beautiful spectacle of all, for those of us who appreciate power, was the sight of the industry’s three leading heavy-duty pickups assembled for us at Bar U Ranch, where we’d have the opportunity to conduct a real-world, head-to-head comparison of their towing capabilities. A similarly spec’d GMC Sierra HD 2500, Ford F250 and Ram 2500 were brought together, each pulling identical trailers upon which sat brand new John Deere tractors.

The total payload was about 10,000 lbs. We were invited to drive each of the trucks along a carefully planned route over the area’s rolling hills and to conduct an exercise that would compare their towing capabilities under real-world conditions.

We lined the trucks up nose to tail (leaving a safe and consistent following distance, of course) and when given the word via radio from the lead truck, buried the throttle. We repeated this exercise several times and each time watched as the lead Sierra HD pulled away from the F250, which in turn distanced itself from the Ram. No one was left in the dust, but the contrast was noticeable and the results consistent.

They were also surprising. After all, the Sierra HD has the lowest published torque among the three models.

Product manager Craig Couch credited the six-speed Allison transmission with giving the Sierra HD the edge. Allison builds what are truly heavy-duty transmissions; the ones found in the Sierra and Silverado would be among the smallest it produces. Because this product was over-engineered for pickup applications, it requires less torque management, meaning it can deliver 100% of the torque produced by the engine right to the wheels.

Horsepower and torque, as displayed on price sheets or proclaimed on advertisements, is measured at the engine and not where the rubber meets the road, which Couch said can be misleading.

“The weaker link of the Ford and the Ram would be their transmission, so they torque-manage,” Couch explained. “They pull fuel in first and second gear to prevent heat buildup, or too much torque for the transmission to handle at a given step in the transmission where it could do some damage. So they put a calibration in, where they’re not utilizing all the torque and horsepower that’s available to the transmission. We don’t torque-manage to the extent the competition does, because the Allison transmission is more than capable of handling the torque demands the Duramax engine puts out. We feel the weak link in the competitors’ drivetrains is their transmissions and it’s the strongest link in ours. Our truck has the lowest stated torque of all three competitors but it actually out-accelerates the competitors because we don’t have to torque-manage and you’re getting all the available torque to the wheels, all the time.”

The difference is especially noticeable in the lower gears – the range in which our comparison was conducted (we let our speed drop to about 80 km/h before getting into the throttle and accelerating back up to the posted limit of 100 km/h, up the steepest inclines we could find). But while the Sierra consistently pulled from the pack, all three trucks were more than capable of getting this hefty load up the hills without labouring. Even GM people admit there’s not a bad heavy-duty pickup to choose from, and when you’re spending upwards of $90,000 for a four- (or six)-wheeler, that’s a good thing.

In addition to offering what they feel is the most impressive low-rpm torque-producer of the class, GM also has spent plenty of effort in building safety and comfort features into their heavy-duty vehicles. This includes StabliTrak with Trailer Sway Control, which comes standard on all new 2015 Sierra and Silverado HDs and an impressive exhaust brake that effectively holds your speed on down grades without burning up your brakes. A driver alert package is also available, including forward collision alert as well as a lane departure warning system that’s unique to the HD segment.

The lane departure warning system produces haptic (vibrating) alerts on whichever side of the driver’s seat the vehicle is straying towards. It gets your attention and is less bothersome to passengers than audible alerts (as if a driver who strays from their lane or fails to signal isn’t bothersome enough).

Both the Sierra and Silverado HD can be loaded up as a luxury personal vehicle used for everyday driving and to tow RVs, boats or horse trailers on the weekends, or they can be utilized as true revenue-producing work trucks. If you’re looking for the ultimate in luxury, then the Denali is your GMC Sierra. The two GMC Sierra Denali 2500s I drove were loaded to the max, were remarkably quiet (especially for diesels) and incredibly comfortable. They were also functional, with loads of power outlets, sensibly placed controls and an eight-inch driver display that provided navigation and sound system info. About 25% of Sierra HD sales feature Denali trim.

On the Silverado HD side, the High Country trim will soon be offered, representing Chevrolet’s first premium heavy-duty pickup. It will feature a chrome grille, unique wheels and an exclusive saddle brown interior with premium materials throughout. This truck will be right at home in Alberta, with its western-inspired colour palette.

If you’re wondering which of the two trucks is the better fit for your image and/or lifestyle, consider that the powertrain is identical so it comes down to your styling preference. The entire front-end clip has a different look, as do the sides of the boxes. The Sierra and Silverado HD are priced comparably and sales are split fairly evenly between the two brands.

The fuel economy achieved on my drive seemed reasonably (generally about 12 litres per 100 kms), but fuel economy in heavy-duty applications is a difficult thing to predict – especially when navigating the undulating hills of southern Alberta. Heavy-duty pickups will perform such varied tasks, that fuel economy will differ significantly. So much so, that truck makers aren’t even required by environmental regulators to publish their fuel economy numbers for anything approved for a gross combination weight rating (GCWR) of more than 10,000 lbs.

The 2015 Sierra and Silverado HD trucks can be ordered with gasoline, compressed natural gas or diesel powertrains, though nearly 60% of customers choose diesel. The Duramax diesel 6.6L V8 engine produces 397 hp and 765 lb.-ft. of torque, which as our drive attested, is easily managed by the robust six-speed Allison transmission. The trucks can haul 7,374 lbs or tow 19,600 lbs (by hitch) or 23,200 lbs (by fifth wheel). Look for the 2015 models of these trucks to hit dealer lots later this year.

James Menzies

James Menzies is editor of Today's Trucking. He has been covering the Canadian trucking industry for more than 18 years and holds a CDL. Reach him at or follow him on Twitter at @JamesMenzies.

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