Driven: 2009 GMC Yukon Denali Hybrid

November 23, 2009
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What weighs three tons, wears 22-inch wheels, and returns 21 mpg in the city? GMC's new Yukon Denali Hybrid.
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The premise of a full-size SUV with the fuel economy of a mid-size sedan isn't anything new. After all, General Motors launched its 2-Mode hybrid system in its Yukon and Chevrolet Tahoe models in early 2008, and the company has slowly rolled the technology throughout its full-size truck portfolio. Cadillac's Escalade received the hybrid treatment later that year, and pickup models - Chevy's Silverado and GMC's Sierra - followed around the same time.
The Yukon Denali Hybrid is a new offering for 2009, allowing GMC to slip some green credibility into its ultimate luxury SUV.
The Denali Look
Attaching the Denali name to the Yukon Hybrid triggers the same changes as when it's applied to a conventional Yukon: not only is the burly SUV treated to body-colored door handles, running boards, and taillamp surrounds, but chrome is liberally slathered across the truck's exterior. Grilles, running boards, door trim, and roof rails are all coated in the stuff, but nothing catches the eye like the massive 22-inch, eight-spoke aluminum wheels (to help smooth the ride, GM fits the Denali Hybrid with magnetically adjusting shock absorbers). Happily, GM has toned down the "Hybrid" insignia to five emblems compared with the Denali's more ostentatiously identified relatives; two of the emblems are simply a stylized "H."
The chrome is conspicuously absent inside, but the Denali's cabin is full of burled wood trim. Not only does the material appear on the door panels, upper dashboard, and center console, the Denali-exclusive steering wheel wraps a band of wood along its outer edge.
What's missing, however, are the cosmetic (and somewhat functional) changes made to regular Yukon Hybrids, for which engineers reshaped the hood, grille, front bumper, chin spoiler, and lightweight wheels in an attempt at reducing drag and improving fuel economy. Few (if any) of these revisions are applied to the Yukon Denali Hybrid -- a shame, as there's quite a bit of energy involved with rotating four wheels sized for the likes of Conestoga wagons.
Green Machinery
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Denali buyers obviously care about exterior image, but we're more impressed with what lurks under the gussied-up skin.
For the most part, these changes are invisible. Don't believe us? Pop the hood -- the most you'll see poking from beneath the sea of plastic beauty covers are traces of GM's 332-hp, 6.0-liter V-8, along with a few bright-orange high-voltage cables. Third-row passengers will also catch a glimpse, as the big plastic bulge encountered while entering and exiting their seats is the 300-volt nickel-metal-hydride battery pack, tucked nicely beneath the second-row bench seats.
But the pièce de résistance -- the 2-Mode transmission itself -- is hidden from view. A shame, for as we've noted time and again, the complicated transmission is a technological wonder, combining a CVT, fixed gearing, electric motors, and generators all into one succinct package.
We'll try to describe it in an equally succinct manner: At low speeds -- say, below 27 mph -- the gearbox functions as an electrically variable transmission, much like the unit in the Toyota Prius. The Denali Hybrid can be powered by either the V-8, one of the two electric motors, or a variable combination of the two power sources.
In the second mode, power primarily comes from the brawny V-8, with one electric motor occasionally working to provide boosts of power during hard acceleration or when towing heavy loads (the second motor acts as a generator to recharge the battery packs). Here, power is transferred to the wheels via four fixed gearsets, which shift and act like a normal four-speed automatic transmission.
Those who tow -- and the Denali Hybrid can pull up to 5700 pounds -- will note the absence of a tow/haul switch on the transmission. Instead, drivers can switch into "manual mode," which gives control over the range of "gears" -- 1 through 4 -- used.
Going the Extra (Green) Mile
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Can all that technology really help such a beastly machine become a fuel miser? Absolutely, so long as your right foot is light enough and speed limits are posted in your favor.
It is entirely possible to launch the Yukon Denali Hybrid only using electric power -- but you'll find that anything short of a snail's pace will trigger the V-8 to awake. This likely won't pose a problem on quiet neighborhood streets or in bumper-to-bumper traffic, but if traffic is bearing down on you at speed, you'll likely find yourself minimizing the time spent in EV mode altogether.
If you're able to find a quiet road with low speed limits -- and we were -- you're in luck. Here, we were able to keep the Denali in EV mode for long stretches without enraging other drivers with our sedate pace. Better yet, we saw fuel-economy averages in the 21 mpg range, the figure quoted by the EPA for city driving.
Sadly, the numbers we saw while cruising on the freeway were slightly less than what's quoted by the EPA. On long stretches of freeway driving, our average tilted more toward the 18 mpg mark. That number did manage to creep up slightly once we slowed our pace from 75 mph to 70.
The transition between the two hybrid modes is smooth -- so smooth, in fact, that unless you keep an eye on the tachometer, you may not detect it. The gauge's needle will appear as if it's performing a downshift and will blip up before plummeting down to the "off" mark.
If there's one thing we wish GM would provide, it's more eco-friendly feedback. A real-time powertrain flowchart can be displayed on the navigation screen, but it doesn't show the battery's state of charge - an informative feature we've seen in other hybrids. Likewise, the "economy gauge" in the cluster is somewhat unusual, seeing as it has no scale or markings other than a green "sweet spot" in the center (we're told that hard acceleration moves the needle to the right, while a sweep toward the left indicates that the vehicle is recharging).
Is the Green Tech Worth The Greenbacks?
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We've professed our admiration for GM's 2-Mode system before, even going so far as to name it our Technology of the Year in 2008. There's no doubt that it's a boon for those who seriously need a full-size vehicle -- it helps allow an automobile that can seat the Brady Bunch, pull a boat, and return some impressive fuel-economy numbers while driving around town.
But it's really hard to advocate the Denali Hybrid itself, largely because of how the full-size sport-ute market has evolved since the Denali line was first launched. Ten years ago, it was difficult -- if not impossible -- to find all the creature comforts of a Denali in other full-size SUVs. These days, it's easy; even a loaded Chevrolet Tahoe LTZ offers similar comforts but at a fraction of the price.
The $64,820 price tag our Denali wore is harder to swallow when you compare its content to that of a Yukon Hybrid. Apart from the chrome bits, the massive wheels, and the wood trim inside, the Yukon manages to offer a nearly identical package, all while shaving nearly $8000 off the purchase price.
The Specs
On Sale: Now
Base price: $61,080
As tested: $64,820
Engine: 6.0L V-8, 332 hp, 367 lb-ft
Motors: 2 x 80-hp AC
Drive: Rear- or 4-wheel

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2009 GMC Yukon

Base RWD 4-Dr Sport Utility V8
starting at (MSRP)
$37,705
Engine
4.8L V8
Fuel Economy
14 City 19 Hwy
2009 GMC Yukon