General Motors’ Bob Lutz places hybrid vehicles third on his five-step fossil fuel addiction recovery program. After making cars more efficient and investing in biofuels but before producing plug-in electric cars and, eventually, fuel cell vehicles, Lutz wants to see GM move into hybrids. With this plan in mind, we decided to spend a few days with a two-wheel-drive GMC Yukon Hybrid.

Though we recently tested the almost identical Chevrolet Tahoe Hybrid, also in two-wheel-drive form, we decided to take another look as we anticipate the upcoming non-hybrid Yukon XFE, or Xtra Fuel Economy.

Both the Yukon and its Tahoe cousin are assembled in Arlington, Texas.

What is it?
GM wasn’t content with simply sticking a hybrid powertrain in the basic Yukon four-door full-size SUV package. The payoff would have been only moderately improved fuel economy. Instead, GM took an extensive look at modifying everything that might potentially drag down efficiency. The result is a Yukon with a unique fascia, a clean roofline and high rolling-resistance tires, among other changes.

Briefly, the Yukon XFE will combine some of the fuel-saving tips learned on the Hybrid in a less-complicated, cheaper, two-wheel-drive-only package beginning this fall.

What’s it up against?
Dodge and Chrysler are releasing hybrid versions of the Durango and Aspen this fall, though neither is quite as roomy inside as the Yukon. Both are also older designs dating to 2004, whereas the Yukon was thoroughly refreshed for 2007.

The Yukon Hybrid also competes with the 2009 Mercedes-Benz GL320 Bluetec, which returns and EPA-estimated 17/23 mpg city/highway, even though the GL320 Bluetec uses moderately more expensive diesel fuel. The Mercedes is only available with four-wheel-drive, whereas the Yukon is available in both two- and four-wheel-drive.

And, of course, there’s the nearly identical Chevrolet Tahoe Hybrid, which stickers for about $500 less than the Yukon.

Any breakthroughs?
Obviously, there’s something unique under the hood (and hidden beneath the middle row of seats). The Yukon Hybrid features a two-mode hybrid powertrain composed of a 6.0-liter V8 engine with cylinder deactivation, an electric motor and a continuously variable automatic transmission. It’s pretty standard hybrid fare, though the cylinder deactivation from non-hybrid versions of this powertrain carry over onto the Hybrid. The Yukon (and Tahoe) was the first V8 hybrid SUV available to consumers.

Aerodynamically, there’s nothing groundbreaking, though GM’s engineers did do a pretty good job making a brick somewhat slippery – the hybrids both feature the lowest coefficient of drag of any full-size SUV at 0.349. The aerodynamic changes also bring down the wind noise just a touch on the highway.

How does it look?
GM says that customers want people to know they’re in a hybrid. We won’t question the motives of the hybrid buyers targeted, but we will question the taste of massive “HYBRID” stickers on both sides of the vehicle and on the windshield and rear window. Our Amana Refrigerator White (officially Summit White) test vehicle might appeal to a NASCAR racer with all of its stickers, but it looks pretty tacky to the rest of us. Fortunately, they’re just stickers and thus can be removed in a matter of seconds. As if the stickers weren’t enough, each side of the Yukon gets a pair of raised chrome Hybrid badges on the fenders and C-pillars.

The Yukon Hybrid gets a different front fascia with a more prominent chrome grille. The front bumper stretches down much, much further than in the standard model, significantly inhibiting any off road pretensions this SUV might have ever had (even though ours was a two-wheel-drive example, the four-wheel-drive models also feature the elongated front bumper). This is, of course, all done in the name of decreasing wind resistance. The running boards are also better integrated into the body with a pair of plastic sail panels designed to help this box cheat the wind and the roof rack is removed. Styling is subjective, of course, but we think the Tahoe Hybrid’s more subtle front end is cleaner and more refined.

Unlike the Tahoe, the Yukon gets black-painted D-pillars. Curiously, both vehicles get the same 18 inch alloy wheel design (albeit with unique center caps) mounted to low rolling-resistance 265/65 Bridgestone Dueler H/T 684II tires. The wheel and tire combination is the same size that’s standard on the upscale, non-hybrid Yukon Denali as well as the new improved-economy Yukon XFE and it’s a step up from the 17 inchers on the standard Yukon.

And inside?
First appearances confirm standard Yukon fare inside. The overall theme is conservative but upscale and comfortable thanks to generous faux (though fairly convincing) wood trim and light tan leather upholstery.

GM’s line-wide navigation system is standard and, in the Hybrid, it contains a separate screen for basic hybrid information and a trip computer. GMC also includes a standard rearview camera that displays through the navigation screen – a handy feature in cumbersome SUVs like this one.

In the instrument cluster, the tachometer drops off below 0 RPM into “Auto Stop” mode when the gas engine is off. A green “economy” gauges takes the place of the battery voltmeter. The gauge doesn’t actually measure anything; it simply gives the driver an idea how efficient they’re driving the Yukon. We had a hard time getting it to move into the “more efficient” end of its spectrum unless we were coasting, so apparently we weren’t too good at economically feathering the skinny pedal.

The Hybrid’s battery packs store beneath the middle row of seats, though third row access is no more difficult than in the standard model. Otherwise, the Hybrid is a standard Yukon SLT inside with few features missing other than power-operated back rests and a power liftgate.

But does it go?
With an extra 20 lb-ft. of torque on tap, the Hybrid makes up for the additional weight of the batteries over a regular Yukon. Unless you look at the gauges, there’s no indication you’re driving a hybrid. Unlike Ford’s Escape Hybrid (and Hybrid versions of the Mercury Mariner and Mazda Tribute) SUV, the transition between electric and gas power is virtually imperceptible. There’s no whine under hard acceleration or when the brakes are applied and the electric air conditioning operates the same regardless of which motor is supplying the power, all issues that afflict the Ford triplets. Kudos to GM for making what we’d consider to be the most seamless hybrid on the road.

In normal driving, there’s simply no noticeable difference between the Yukon Hybrid and a standard gas-only model. The only indication you’re saving fuel is when the tachometer needle drops below 0 RPM into “Auto Stop” to indicate that the electric motor is supplying all the power. We were able to get up to about 28 miles per hour using just the electric motor with especially light application of the throttle.

Handling-wise, it’s pretty much the same as the standard Yukon. The Hybrid has electric power steering rather than hydraulic, but in a big SUV, it hardly makes a noticeable difference in terms of drivability. In fact, with the claimed (admittedly minor) fuel savings of electric power steering, we aren’t quite sure why GM doesn’t just go ahead and put it on all their large SUVs. Unlike in cars (Pontiac G6 comes to mind), putting electric power steering in a cumbersome SUV wouldn’t sacrifice road feel. If GM thinks it’s reliable enough for the hybrids, why not spread it across the line?

We averaged about 18 mpg in the city – a fairly respectable number for such a big SUV, though hardly one that would repay the price hike for the electric assistance. On the highway, we barely managed 18.3 mpg over a 100-mile run, probably no better than a non-Hybrid model.

Why you would buy it:
You have a need for a big SUV and you spend a lot of time driving in urban areas where the hybrid will use less fuel.

Why you wouldn’t:
Since that need above describes roughly one in 100 people who buy SUVs, you’re probably best off saving your money and going with the standard Yukon. Still, we know that our arguments won’t dissuade thousands of suburbanites comforted by the Yukon’s mass and interior room – and those huge Hybrid stickers.

We certainly applaud GM for bringing to market a “no compromises” Hybrid and we hope that they’ll continue to take some of their fuel-saving techniques gleaned from this project and apply them to other vehicles – even those not electrically motivated like the upcoming XFE models.

2008 GMC Yukon Hybrid 2WD base price: $50,045, as tested: $53,235. Options as tested: Rear-seat DVD player, $1,295; Power sunroof, $995.

Words and photos by Andrew Ganz.

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