GMC SIERRA DE­NALI 2500

4 x 4 Australia - - Driven -

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.

OFF-ROAD

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.

PRAC­TI­CAL­I­TIES

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.

SUM­MARY

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.

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