2011 GMC Sierra Heavy Duty: First Drive

Huw Evans
by Huw Evans

When you’ve been building trucks since 1902, it’s probably fair to say you’ve got a bit of experience when it comes to finding out what customers want and need from a heavy-duty pickup. For 2011, GMC unleashes an updated Sierra HD, which while sharing many improvements with its Chevy Silverado cousin; offers a few party tricks of its own.


1. A new 6.6-liter Duramax makes 397-hp at 3000 rpm and 765 ft-lbs of torque at 1600 rpm and comes with an integrated exhaust brake.
2. Maximum payload capacity on the 2011 Sierra HD is 6,635 lbs, with max fifth wheel towing rated at 21,700 lbs.
3. Stabilitrak and hill start assist are standard on all single rear wheel Sierra HDs
4. Denali models come in just three exterior color choices; Black; Stealth Gray or White.

According to manufacturer research, within the parent company, GMC truck customers differ somewhat from their Chevrolet counterparts. They tend to be younger, more affluent and more Internet savvy, with a preference for more features in their trucks.

As a result, the Sierra HD trim and equipment levels differ from the Silverado, with W/T (Work Truck), SLT and SLE trim levels, plus the luxury oriented Denali. Prices start at $27,965 for the base work truck (before options, taxes and fees), while by contrast, Denali models, now offered in both ¾-ton (2500) and 1-ton (3500 configurations), begin at $45,865. 2011 Sierra HDs are offered as regular, extended and crew cab models, with a choice of 6.6 or 8.2-feet boxes. Denalis are only offered as crew cab models and only with 4×4 drivelines.


Styling, while similar to Silverado at a glance, is in reality quite different, with front and rear fenders, the hood, grille and bumper assembly unique to Sierra. For 2011, HD GMC pickups adopt a new design of grille with three horizontal bars, a redesigned front bumper and re-sculptured hood with a pronounced plastic center section at the rear (Chevy trucks have two smaller bulges on each side). Denali models sport a unique chrome grille with four bars, a greater use of chrome accents, plus a body colored front bumper with built in foglights, along with a polished finish on the standard 17 and optional 18 and 20-inch wheels (including dualies).

In terms of fit and finish, both outside and in, W/T, SLE and SLT Sierra HDs, generally mirror their Silverado counterparts. Workmanship is decent, with fairly precise panel gaps and good paint finish on the trucks we sampled. Inside, all boast an ergonomically sound cabin with a logically laid out instrument cluster and center stack, plus comfortable and supportive seats (even in the base truck). However, the cabin still has somewhat of a low rent feel to it, particularly where the top of the dash surface is concerned and the glove box door, which features a rather flimsy handle.

Denali trucks up the ante with such features as power adjustable pedals, 12-way power front seats, a Bose premium sound system, plus specific Denali aluminum trim. Heated and cooled front chairs are available on SLT and Denali models, adding a welcomed addition of comfort, no matter what the weather conditions outside. In terms of interior space, the GMC Sierra HD fares rather well, with over 41-inches of front headroom in all cab configurations and 41.3-inches of front passenger legroom. (Rear riders have more than 39-inches to stretch their legs in crew cabs). The rear seat on extended and crew cab models also folds up – ideal for those times when you need to carry home bulky items that need protecting from the elements.


As tough and dependable as the 2010 model was, GM engineers, caught in a battle for supremacy with Ford’s new Super Duty, have gone to town on the HD’s greasy bits.

For starters, there’s a completely new frame. Unlike the old one, this is fully boxed, with longer chassis rails and larger, sturdier crossmembers designed to increase torsional stiffness five fold over the previous truck’s chassis. In addition, extended and crew cab models get new hydraulic body mounts, in an effort to reduce vibration and shocks being transmitted up into the interior. Mounted on the new frame is a new suspension, both front and rear, with a wider wheel track to improve stability. Up front, new upper control arms made from forged steel are both lighter and stronger, while the torsion bar springs can now be configured in no fewer than five different spring rates, enabling the front axle to obtain a weight rating capacity of up to 6,000 lbs, meaning that it’s more than capable of handling heavy front end equipment; including snow plows. There’s also a revised steering assembly, with specific pumps for diesel and gas engined trucks.

Out back, a pair of new asymmetrical leaf springs, which are 20 percent wider than those on the old truck, are designed to maximize weight loading, while maintaining a comfortable ride, thanks to specific shock tuning. 2500 series trucks feature two stage springs, 3500 models use three-stage springs to support their heavier payload capacity with 7,050 lb gross axle ratings on single rear wheel models, 9,375 lbs on dualies.


In terms of powertrain offerings, GMC is following industry practice by simplifying engine and transmission choices. Unlike Ram, a manual gearbox is no longer offered and just two motors are available, a 6.0-liter Vortec V8 gasoline engine, and a 6.6-liter Duramax Turbo Diesel.

The Vortec (standard equipment in all ’11 Sierra HDs) is essentially unchanged from last year, rated at 360 horsepower at 5400 rpm and 380 ft-lbs of torque at a relatively high 4200 revs. The 6L90E six-speed automatic; has been strengthened with a new, stouter input shaft and on 4×4 models, a bigger adapter and bosses for the transfer case. The Vortec V8 is smooth, with a nice authoritative rumble under throttle, but what does surprise, is that for a pushrod engine, it’s quite peaky, requiring a healthy amount of accelerator input to really get this truck moving. But once in the sweet spot, it’s got plenty of go. Making it easier is a manual shift feature on the six-speed automatic with push button activation; that can act as an engine brake on downhill sections.

The optional Duramax 6.6-liter diesel (a fairly pricey one at $8,395 we might add); has been more substantially revised. New moving parts, included revised pistons and rod pins, plus oil circulation both for the engine and variable nozzle turbocharger, have been improved to reduce friction and increase smoothness. A high-pressure fuel system is designed to boost performance (power is now 397-hp at 3000 rpm and torque a mighty 765 ft-lbs at just 1600 rpm); while combined with a new Diesel Exhaust Fluid injection system, the result is said to be a more than 60 percent reduction in the amount of oxides of nitrogen through the tailpipe.

The new Duramax is an impressive piece. Acceleration is gutsy – the torque is right there when you need it and hauling or towing substantial loads behind the truck is a snap. Acceleration is noticeably quicker than the 2010 version, with GM claiming 0-60 mph times of under 9 seconds.

All Duramax engines are backed exclusively by an Allison 1000 series six-speed automatic, that incorporates a manual shift feature like the 6L90 fitted to gas trucks, plus a more efficient tow/haul mode for better shift control and cooling when pulling a load. GMC rates the Duramax equipped Sierra HD at a max towing capability of 21,700 lbs (with a fifth wheel coupling), 17,000 with the conventional Class IV hitch.


With a 4,000 lb. load in the bed, negotiating fairly steep grades in an around the Maryland/West Virginia border proved to be no problem, aided by a neat new feature – an ‘intelligent’ exhaust brake. Linked with the truck’s cruise control system, this exhaust brake uses compression pressure from the cylinders, along with exhaust gases from the turbo to spike the revs and slow the truck down. With the cruise active it’s able to vary engine speed according to the grade and is mightily effective – we barely had to tap the brakes most of the time – even when a 20 foot camping trailer was hooked to the back of our test vehicle.

In terms of overall driving characteristics, GM’s engineers have delivered what is a very well rounded package. By heavy-duty pickup standards, the Sierra delivers a great blend of ride comfort, agility and braking. On our sample roads, the suspension was nice and compliant, devoid of the rear end jitter that’s often evident on this class of pickup. Steering was also nice and direct, without being harsh at slow speeds, often a difficult aspect to muster. On the highway, directional stability was very good, unlike the truck’s two main competitors, plus thanks to enlarged brakes (14-inch discs at all corners), stopping ability was also well above par with good pedal feel. Combined with the exhaust brake, it’s likely you’ll never have to worry about cooking the anchors when pulling a heavy load behind you down a steep hill.

As for fuel mileage, GM says that the new Duramax delivers around 10 percent better fuel economy than its predecessor, but although we weren’t able to accurately measure mpg, GMC has fitted all Sierra HDs with a 36-gallon fuel tank. Based on manufacturer testing, it’s said that a Duramax equipped HD can now go a distance of 680 miles between fill ups, which should be a welcomed benefit to those who do a lot of long distance contract work or hauling.


Although it might not have the flash of either the Ram HD or Ford Super Duty, the 2011 Sierra HD eschews style for substance. Thanks to its thoroughly updated skeleton, improved suspension and stronger diesel powertrain, it’s one capable all-around pickup, with options and features to suit almost any requirement or budget. Plus the Denali editions add a certain understated cachet that’s hard to find in the real truck segment.


2011 Ford F-Series Super Duty: First Drive
2010 Dodge Ram Heavy Duty: First Drive


  • Torquey and quiet Duramax Diesel
  • Superb braking ability
  • Huge choice of options and configurations


  • Interior still feels cheap
  • Still some buffeting under braking when towing (even with the factory Trailer Brake Control)
  • Diesel Exhaust Fluid needs replenishing every 5000 miles
Huw Evans
Huw Evans

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