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.