The 2008 GMC Yukon Hybrid is either the first guilt-free full-size SUV or an example of unrestrained excess. The Yukon is big, with three rows of seating and a cliff-like front-end. And it uses one of the bigger engines available in the Yukon line, a 6-liter V-8. But it adds GM's new two-mode hybrid system to give it surprisingly good fuel economy. In city traffic, we're talking close to 20 mpg. Good thing it has all those hybrid labels around the body to fend off public rancor.
The cabin electronics are the same as GM has been offering on its bigger vehicles, with a touch-screen LCD and an easy-to-use tabbed interface for accessing navigation and audio functions. The Yukon Hybrid also gets a decent Bose stereo, but it relies on OnStar for hands-free calling.
Test the tech: Emissions-free cruising
Unlike previous mild-hybrid systems from GM, the GMC Yukon Hybrid's two-mode drivetrain is a full hybrid system, capable of driving the vehicle under electric power only. The driving experience is very similar to that of a Toyota Prius, where the engine will shut off at a stop and initial acceleration is handled by the electric motor. To really test the Yukon Hybrid, we tried to see how long we could drive it before the engine kicked in. Our test drivers, editors Wayne Cunningham and Antuan Goodwin, would have to keep the acceleration very light, as the engine will kick in whenever more than moderate pressure is applied to the gas pedal.
The test would also be limited by how much juice the battery held, as the system is designed to turn on the engine whenever the battery gets below a certain charge level. As we went to start our test, we noticed an initial hurdle: there is no gauge on the car to show the available charge on the hybrid battery pack. Before each run, we tried to get it charged up as much as possible by building up some speed then lightly applying the brakes. The Yukon Hybrid uses regenerative braking and we were able to see from the power-flow animation when the battery was being charged.
Goodwin took the first run, stepping up into the high driver's seat and getting behind the wheel of the big truck. From a stop, he put light pressure on the gas pedal and the Yukon edged forward. The tachometer remained in the engine stop position as the vehicle climbed past 10 mph. It cruised down the long straightaway of our test loop, building speed slowly up to 25 mph. With such a big vehicle, it was hard to believe we weren't burning any gas. The first turn on our loop went over a section of unpaved road, which added resistance to the wheels, slowing the car and tempting Goodwin to apply more gas pedal pressure. He eased it up, avoiding an engine start, and the Yukon continued to roll. But he got too greedy on the return straightaway, blipping the gas pedal enough to make the engine kick in. His total electric drive time was 2 minutes, 50 seconds.
Next up was Cunningham, again getting the big Yukon going slowly at first, keeping acceleration light so that the engine wouldn't kick in. The easy cruise down the first straightaway went by at speeds between 20 and 25 mph, but the resistance of the unpaved turn forced him to apply more pressure to the gas pedal. The Yukon Hybrid kept rolling under electric power, clearing that section and starting up the return straightaway. The car rolled noticeably easier on the pavement, and Cunningham kept light pressure on the gas. Just short of one lap, the engine kicked in, most likely because of a drained battery, finishing off the run at 4 minutes, 33 seconds.
We were impressed that the 5,617-pound Yukon Hybrid could be driven under electric power only for close to 5 minutes. We think it could go even longer if the battery was fully charged.
In the cabin
The cabin of the 2008 GMC Yukon Hybrid differs little from its mundanely-engined model-mates. It comes close to luxury, with leather seats and nice wood trim. Third-row seats are removable, creating a massive cargo area. Although GMC sells base-trim Yukons with standard engines, the Hybrid version comes fully loaded, with a navigation system and Bose audio. The only option on our test car was a power sliding sunroof.
We've seen the Yukon Hybrid's DVD-based navigation system in other GM models. It works very well, but is far from the cutting edge. Its maps are a little rough-looking and it doesn't show traffic information or read out the names of streets. But one of our favorite features is the split screen, showing the map on one side and audio information on the other. Destination entry is somewhat limited, only letting you pick points on the map, select points of interest, or manually enter an address. But the system is also tied in with OnStar, so that when you call the service for directions, the destination will be downloaded to the navigation system. Route guidance works well, with easy-to-read graphics and a good amount of warning time before turns.
The LCD also works as the interface for the audio system. For audio sources, you get an in-dash CD player, XM satellite radio, and an auxiliary audio input. Real iPod integration isn't an option. But this system has one unique trick up its sleeve: it can scan an MP3 CD and let you select music from it with an iPod-like interface. After a CD is scanned, you get to choose from a list of artists, albums, and genres, provided the MP3s have proper ID3 tagging. The only drawbacks to this feature are that it takes a while to scan a CD--up to 5 minutes--and you have to rescan the CD if you eject it then put it back in. We really like the usability of the music selection interfaces, too. The system makes it very easy to choose a category from XM or browse music on a CD. Given the quality of the interface, iPod integration would be really nice.