2016 GMC Sierra Denali 2500HD Review: Performax RHD conversion

Rating: 8.0
$152,000 Mrlp
  • Fuel Economy
  • Engine Power
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The GMC Sierra Denali 2500HD big rig, converted to factory-standard RHD by Queensland's Performax, has been billed as the 'Cadillac of trucks'
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Some people need a work ute that can handle more of everything than the Toyota HiLux, Ford Ranger, Mitsubishi Triton and co. That’s where huge American pickups such as the GMC Sierra Denali 2500HD roll in.

Imported and converted to right-hand drive by established Queensland-based company Performax International, the GMC Sierra Denali is one of a wide swathe of US trucks available in Australia through similar channels.

Companies such as Performax — which offers an array of big rigs such as the Chevrolet Silverado, Toyota Tundra and Ford F-Series — as well as the newer American Special Vehicles (ASV) joint-venture to sell Ram trucks, fill an obvious void in the mainstream market.

The GMC Sierra range naturally competes with all of the aforementioned offerings, with what feels and appears to be a rather upmarket bent. In an era where pickups are often emblematic status symbols, the bling-laden GMC looks tailor-made.

In fact, one of the more reputable US automotive publications out there recently called the GMC Denali the “Cadillac of trucks”. At $152,000 plus on-road costs, it’s $2500 more than Performax’s converted (and top-selling) Chevy Silverado (the GMC’s sibling) and Ford F-250 Lariat, and $12,000 more than ASV’s similarly capable Ram 2500. Or 2.5 x Ford Ranger Wildtraks.

At home Stateside, the GMC Sierra is number four in the market behind the Ford, Chevy and Ram. But even this spot denotes a staggering 224,139 sales in the US alone during 2015 — equivalent to about one-fifth of the entire Australian new vehicle market.

Given all of these huge US trucks are capable of ferrying and towing loads that would make a Toyota HiLux baulk, the specific technical specs perhaps take a back seat to other considerations. The GMC might well appeal simply because it’s less widely known than the Ford F-Series.

A little about Performax before we get stuck in. It bills itself as “the largest independent importer, converter and retailer of selected American vehicles in Australia” and a leader in the conversion industry for 25 years. Though Walkinshaw-backed ASV will no doubt prove stiff competition.

It produces its wares in a 2500 square-metre facility with 60 staff aiming to produce cars to OEM standard, and every re-engineered part specific to RHD vehicles has a specific part number and is consistent.

A typical conversion requires around 300 new components, including items such as: firewall, lights, lines for brakes/power steering/air, brackets to mount systems such as the new power steering, head units for navigation, moulded parts and fasteners. There are around 27 unique new moulded parts including dashboard, wiper cowl, switch panels and air-con ducting. These are developed at Performax Gympie and injection-moulded to "OE quality" in China.

Our test GMC met Full Vehicle Compliance requirements. This sorts the conversion house wheat from the chaff, because the demands are more stringent.

Right away, the GMC is an impressive-looking bit of kit, imposing in a similar vein to the Ram we drove recently. A vast chrome grille (remember, this is an upmarket truck in the States) with matching wheels and huge mirrors, floodlights on the bumper bright enough to see through brick walls, dark tint and a tail pipe almost big enough to stick a footy in.

Under the bonnet is a 6.6-litre V8 turbo-diesel with a thunderous 298kW of power and 1037Nm of torque from only 1600rpm — 22kW more than the Ram 2500’s 6.7 Cummins turbo-diesel six, but 47Nm less torque at the same engine speed. The big V8 gets a battery with rundown protection and retained accessory power, and a 150 amp alternator.

This massive engine has more than double the capacity and displacement of a HiLux 4x4, and more than double the torque of even the most potent of the current crop of mainstream 4x4 utes — the 500Nm Holden Colorado.

It’s matched to an Allison 1000 series six-speed automatic transmission with a par-for-the-course column shifter, and in-built tow mode. The drivetrain is complemented by a shift-on-the-fly, dial-operated 4x4 system and an Eaton auto-locking rear diff with 3.73 ratio.

The engine is a beast of a thing. It’s not as immediate or crisp as some off the line, but it has a deep reservoir of torque that comes on in a steady and unrelenting surge, and bellows a satisfyingly ballsy V8 rumble throughout its rev band. Consider that, even unladen, the GMC’s tare weight of 3.4 tonnes is more than 50 per cent greater than a HiLux.

Our (unladen) fuel economy drive loop, with 70 per cent country and 30 per cent urban driving, returned around 13.0L/100km, matching the Ram more or less. Which is bloody impressive for a V8 diesel engine. Our tester had an optional 215L long-range fuel tank ($3000).

The heavy duty gearbox is proactive, ever-eager to shift up through the ratios quickly to tick along at the lowest revolutions, but also quick to adapt to loads or more aggressive driving. The decisiveness, and the lack of driveline shunt that accompanies, is impressive.

With the correctly rated towball, you can tow a 4.5-tonne braked trailer — a tonne more than the top-rated mainstream, smaller ute, and sufficient to match the Ram. But to show the potency of this engine, the larger 3500 model with the same powertrain is rated capable of towing a staggering 10.5-tonnes with a fifth-wheel setup.

While that 4.5t rating as driven doesn’t necessarily seem vastly superior to something like the 3.5t Ranger, HiLux and company, keep in mind that the GMC is clearly capable of doing this chore in a relatively unstressed manner, as its potential ceiling is vastly higher.

You also get tow-friendly features such as a diesel exhaust brake (again, matching the Ram) that works down the gears, an integrated trailer braking system and a trailer-sway control system built into the ESC.

Dimensionally, the Denali about matches the Short Box version of the Ram 2500, at 6.1-metres long (600mm longer than a Ranger), 2041mm wide and 1987mm tall, on a 3904mm wheelbase. There’s really nothing this side of a heavy duty truck this big.

The tray is two-metres long, and the payload is 1145kg, or about 300kg more than a Ranger Wildtrak. You get four moving, high-mounted tie-downs and LED lights in the cargo box for night work, though the spray-in bed-liner is only optional. It shouldn’t be.

Once you’ve adjusted to the dimensions, the GMC is simple enough to drive, though its five-leaf rear suspension gets a little choppy when unladen — though bump absorption on impact at the front is quite well-sorted even on 20-inch alloys wrapped in Goodyear rubber — and the power steering still has a fair bit of resistance. The turning is circle is unwieldy.

But on a long stretch of highway or a B-road, the noise insulation is sublime (triple seals and thick glass), while city driving is abetted by the commanding road view and the brilliant double lens side mirrors with lower sections trained on the road lines. It’s scarcely harder to get around in than a HiLux once you adjust.

Driving at night is an… illuminating experience. Standard-fit is a halogen projector beam that supplements the high beams, fitted in the front bumper, that rivals the surface of the sun for brightness, though it’s operated by an incredibly shonky switch.

Jump in the five-seater cabin and it’s fairly clear that the GMC is indeed an upmarket vehicle, as fits its price. In true high-end US pickup style, it comes fairly loaded.

Dual-zone climate control, an 8.0-inch touchscreen with Australian sat-nav SD card, reversing camera (but not the Ram’s cool tray cam) and all-round sensors, a heated steering wheel, cruise control, keyless entry (but not start, given the horribly old school key), sunroof, Bluetooth and five USB points, and heated/cooled perforated leather seats.

There’s also the US nav software and GM OnStar tech, which is novel but useless. And the Bose seven-speaker sound system with sub has excellent clarity, bass and is even synced to a homepage with a decent interface.

On a safety front, you get six airbags including rear curtains, and impressive active safety for a ute, including lane-departure warning, a collision avoidance warning system with head-up messaging and a safety alert warning that vibrates the seat if a crash warning is prompted, or the reversing sensors are honing in an object. How intimate.

The layout of the cabin is pretty spot on, from the nicely trimmed wheel with buttons, to the ample instruments with digital speed readout, the big leather buckets, adjustable pedal box, large touchscreen and smattering of deep and well-placed storage areas.

It's a designer office, for the most part, though beyond the shonky lightbar switch, there are also some average squeaky door plastics and some buttons not for the tactile among us. Things are no different in the Ram, though. It seems to be a US pickup thing. The placement of all the key buttons, notably the 4x4 mode switch and trailer brake controls in a bank to the right of the wheel, is bang on.

The conversion itself seems OEM standard. Gaps, rogue trim and ergonomic oddities are absent (save the back-to-front AC Sync buttons and extraneous US-spec software bits... we're clutching at straws here), and the foot-operated parking brake is properly fitted to the left of the foot rest.

Unlike the Ram, the huge console doesn't flip down to render the front a bench seat. But the rear three seats are equally excellent, with plenty of room for three adults, child-seat attachment points, lots of storage (though no dedicated vents), a sliding back window and seat squabs that flip up to turn the whole affair into a giant King Cab.

From an ownership perspective, Performax puts its money where its mouth is, with a four-year/120,000km warranty, 24-hour roadside assist, 16 national dealerships with service centres selling and supporting its conversions and a sizeable local parts inventory (though some parts will have to be flown in from overseas, in between 7-10 days).

So that's the GMC Sierra Denali 2500HD. It's a little pricer than ASV's RAM 2500 and doesn't stack up necessarily as any more capable. But Performax's conversion job seems spot-on, and it's an established player with ample experience.

In the GMC's favour is its imposing design and its upmarket positioning. It's basically the ultimate lifestyle ute, a chromed-up Cadillac that can haul basically anything.

We wish car brands such as GM, Ford and Chrysler would import these big rigs directly through their own channels as factory right-hand drive, not because of any real quality gains, but mostly because they'd be cheaper than $152K. But in the meantime, the Performax, like the ASV, feels like a very worthy substitute.

Click the Photos tab for more images by Tom Fraser.