Purchasing an earlier General Motors hybrid model could perhaps be equated to buying tickets to see Kiss, only to discover it's actually a tribute band made up of four guys from Ann Arbor. While GM's models like the Saturn Vue Green Line may have worn hybrid regalia, their gasoline-electric technology was unsophisticated and underpowered compared to "full" hybrids from Toyota and other carmakers. With its all-new Two-Mode hybrid technology, the 2008 GMC Yukon Hybrid is the real Gene Simmons deal. A new approach to hybrid design helps create a full-size SUV that gets fuel economy in the 20s, carries eight people and tows 6,000 pounds.

At the heart of the Yukon Hybrid is the "Two-Mode" technology co-developed by GM, BMW and DaimlerChrysler. Completely understanding the differences between this two-mode system and other "full" hybrid systems basically requires an engineering degree, so if you couldn't care less how it works, skip the next two paragraphs.

As with a regular Yukon, you'll find a V8 under the hood. But this 6.0-liter V8 has cylinder-deactivation technology (it turns a V8 into a V4 when full power isn't needed) and is supported by a pair of 60-kilowatt motors packaged within the transmission to provide the electric motivation. Dubbed an electrically variable transmission (EVT), it features those two motors, three planetary gearsets and four traditional hydraulic wet clutches.

The EVT is essentially like having two transmissions inside one -- continuously variable drive for light load conditions and fixed-ratio for high load conditions. Hence two-mode. The hybrid system then constantly receives data from the powertrain and other vehicle systems to determine the most fuel-efficient means of propelling the vehicle -- be it electric power, gasoline power or a combination of the two. And like other hybrid models, there's a battery pack for storing power, regenerative braking to take advantage of momentum, and the ability to shut off the engine when the vehicle is stopped.

For those who skipped ahead, welcome back. The moral of the above story is that a 5,600-pound full-size SUV returns fuel economy better than most large crossovers. City mileage is particularly impressive, and like most hybrids, is about equal to highway mileage. This is the result of being able to accelerate up to approximately 25 mph using electricity only, a fuel-saving asset on surface streets and in stop-and-go traffic. If that's your driving domain, the Yukon Hybrid makes a lot of sense.

In addition to improved fuel economy, the 2008 GMC Yukon Hybrid boasts more power than its gas-only brother. However, don't expect much better acceleration, as the hybrid tips the scales at a hundred or more pounds heavier than a fully loaded Yukon. That's despite GM's best efforts to cut weight by constructing several body panels of aluminum and trimming heft from the seats (though ironically not from the heavy removable third-row seats, which could use a nip and tuck).

Other than its sophisticated running gear, the Yukon Hybrid is essentially a fully loaded Yukon SLT. The only options are a sunroof and DVD entertainment system, with niceties like leather, a rearview camera and navigation system standard. However, the price premium is significant, ringing in at about $8,000 more than a similarly equipped gas-only Yukon. (It's also about $900 more expensive than its Chevy Tahoe sibling without offering anything extra aside from GMC's "Professional Grade" slogan.) Although the fuel economy difference is also commendable, it will take a lot of miles/years for your gas savings to justify the out-the-door premium. We'll let you decide if the environmental benefits are worth the price, but how green can a 5,600-pound SUV really be?

So, unless the 2008 Yukon Hybrid's significant towing capabilities are important, a full-size crossover like the GMC Acadia may be a better choice. It provides more usable passenger space, is friendlier to drive, gets close to the same fuel economy and is $8,000 cheaper when loaded to the gills. The new two-mode hybrid system is certainly impressive, but we're not entirely sure if the Yukon is the right vehicle for it.

The 2008 GMC Yukon Hybrid is a full-size SUV available in one trim level. Standard equipment includes 18-inch alloy wheels, rear parking assist with rearview camera, tinted windows, power-folding heated side mirrors and tri-zone automatic climate control. A trip computer, an auto-dimming rearview mirror, remote ignition, leather upholstery, power front seats and a removable 50/50-split third-row seat are also standard. In-car entertainment includes a navigation system, a hybrid system display and a nine-speaker Bose audio system with CD/MP3 player, auxiliary audio jack and satellite radio. A sunroof and rear-seat DVD entertainment system are the lone options.

The 2008 GMC Yukon Hybrid is available with rear-wheel or four-wheel drive. Both models utilize a 6.0-liter V8 engine coupled to a pair of 60-kilowatt electric motors located inside what GM calls an electrically variable transmission. Together they produce 332 horsepower and 367 pound-feet of torque. The system can accelerate the Yukon up to speeds of approximately 25 mph using electricity only, while the V8's cylinder-deactivation system helps reduces fuel consumption at higher speeds. Regenerative braking replenishes the batteries by capturing energy normally lost when coming to a stop. Fuel economy is 21 mpg city and 22 mpg highway for rear-wheel-drive Yukon Hybrids and 20/20 with four-wheel drive. Maximum towing capacity for a properly equipped 4WD model is 6,000 pounds.

Standard safety equipment includes full-length side curtain airbags, antilock disc brakes, traction control, OnStar and a rearview camera. In government crash testing, the Yukon Hybrid scored a perfect five stars in all frontal and side impact tests.

It's not a stretch to say that driving the 2008 GMC Yukon Hybrid feels like being behind the wheel of a 5,600-pound Prius. There's the same eerie quiet when accelerating and braking, as the gas engine shuts off to let the electric motors do their thing. Although a tad strange, the result is a quiet cabin, while transitions between gas and electric modes, and eight- and four-cylinder mode, are either undetectable or easy to ignore.

The regenerative braking system produces a firm braking feel and, according to GM, actually stops the big SUV better than the regular Yukon's conventional brakes do. Although the Hybrid is the most powerful Yukon available, it's also the heaviest, so don't expect particularly brisk acceleration. Still, its abundance of low-end power -- aided by those torque-rich electric motors -- produces plenty of "motorvation" for around-town chores and trailer towing.

Aside from instrumentation, there's nothing to distinguish the Yukon Hybrid from a traditional Yukon. Unlike in past generations, that's a very good thing. The newest Yukon boasts attractive, high-quality materials and tight panel gaps while maintaining a simple control layout. Even the standard navigation system is easy to use.

With its standard third row, the Yukon can seat up to eight passengers. Unfortunately, that 50/50 third row does not fold flat into the floor. Since the two seats weigh slightly less than a Geo, you'd better have Steve Austin on standby to help remove them. Once they're out, though, maximum cargo capacity is a whopping 109 cubic feet with the folding second row down -- much more than any other hybrid offers.