GMC SIERRA DENALI 2500
The Denali climbed with confidence, its locking rear end pushing the truck onward and up
GMC is the truck brand for General Motors, and the Sierra is basically a Chevrolet Silverado with a different face. Denali is the upper-spec range, so it adds more bling and safety features, but the chassis and drivelines are the same between the two trucks. Performax, who converted and supplied this truck, told us that a Silverado built to the same spec would sell for around $2K less than the Denali’s $152,000.
DRIVELINE & CAPACITIES
THE GMC Denali and the Silverado both use GM’S Duramax 6.6-litre turbo-diesel V8 mill. Forget that Holden borrows the Duramax brand for its small Italian-made diesel engine – this V8 is the real Duramax deal. 1037Nm and nearly 300kw might be a tad short of the Ford’s figures, but the GMC wants for nothing. It will still haul an 8.0-tonne trailer or carry a 1.6-tonne payload, but, like the Ford, these are down-rated to a 4.5-tonne GVM to allow Aussie drivers to operate it on a regular licence.
The Duramax is backed by a six-speed auto transmission from heavy-duty driveline experts Allison. It has a towing mode, as well as an exhaust brake, to help slow the beast when towing down steep grades. It also makes you sound like a real truck driver! The rear axle in the Denali has an auto-locking differential from Eaton, while ETC is part of the chassis electrics package.
CHASSIS & HANDLING
WHILE these three heavy-duty pick-ups may appear to be built to the same formula, they each feature different underpinnings. The GMC rides on a separate ladder chassis and, like the F-250, features a live rear axle on an HD leaf spring pack. However, it differentiates itself from the other two by using an independent front suspension design with torsion bar suspension. This is more like the one-tonne utes we’re familiar with here, although most of those have now ditched torsion bars in favour of coil springs.
The IFS gives the GMC a more controlled and less truck-like ride and demeanour on-road, with less kick-back through the steering and a sharper feel. For anyone not accustomed to driving large, live-axled trucks, the Ifs-equipped GM products will be the easiest to adapt to.
WITH IFS, we expected the Denali to struggle on our off-road climb, but it didn’t disappoint. While not as supple as the Ford, the Denali climbed with confidence, its locking rear end pushing the truck onward and up. The rear axle also has plenty of articulation, which helped its cause, keeping those big 20-inch tyres driving. This particular vehicle is privately owned and the owner has
fitted Goodyear All-terrain tyres and Rancho shock absorbers, which would have helped it. The pair of LED light bars up front are also owner-fitted. THE Duramax V8 develops a deep-throated snarl under load, and it hauled our car and trailer up the Brisbane Ranges with aplomb. The independent front end of the GMC gave it the best handling under load, and the six-cog Allison tranny joined in to help the Denali haul confidently and comfortably. The tow setting on the transmission, along with the exhaust brake, made the descent a cinch.
CABIN AND ACCOMMODATION
THERE’S no denying the size of the cabins in these trucks, and the GMC is large and luxurious. Heated and cooled poweradjustable seats, plenty of storage options, heated steering wheel and dual-zone climate control – there’s nothing missing from the Sierra Denali.
Something we don’t see in smaller utes are adjustable pedals, and all three of these trucks have electric adjustment to bring the pedals closer to, or further from, the driver’s seat.
This Denali is fitted with the optional Driver Safety Alert Package, which is a no-cost option from Performax. It adds lane departure warning and forward collision warning, and the warnings are accompanied by a vibration in the seat base – left cheek if you veer left, right cheek for the right and a warning if you’re approaching an object in front of you. This is the only truck here with that sort of safety technology.
The Denali uses GM’S Onstar system, and Australian maps can be loaded onto it. It also uses Apple Carplay to sync with your Apple device; the sound pumps out through a Bose speaker system. Soft touchpoints throughout the cabin give the Denali a premium feel.
265/60R20 Goodyear Wranglers wrap around big chrome wheels, so it’s not a common tyre size here in Australia. The engine breathes through the offside front ’guard, but the aircleaner requires a screwdriver to gain access. The owner of this GMC has fitted an aftermarket dual-battery system, with the auxiliary battery mounted in the engine bay.
There are two heavy-duty tow points in the front bumper and a received hitch can be used at the back. The tray has a spray-on bed liner, with four tie-down hooks for securing loads. The step indents in the sides of the rear bumper – to make stepping into the tray easier – are a clever touch. However, they’re not as cool or complex as the Ford’s fold-down step.
THE GMC Denali is the most luxurious and user-friendly of the trucks in this trio. The IFS makes it more manageable on the road, particularly for drivers not used to live-axle trucks, while the fit-and-finish and equipment level inside give it a premium feel. It surprised us with its ability on the off-road hill climb, while out on the road its Allison 1000 transmission felt the best of the group – both when towing and unladen. Consuming 17.18L/100km during our test, the GMC was the most frugal of the trio.
Performax backs its vehicles with a four-year/120,000km factory-backed warranty, which includes 24-hour roadside assistance on new vehicles.
The Denali felt the most composed onroad and when towing.
A big donk under the hood helps haul bigger loads in the tray.