Highs: Good fuel economy for a full-size SUV, smooth ride, comfortable interior.

Lows: Disconnected feel, average handling, small third row seat.

We have always been fans of the Chevy Tahoe and GMC Yukon. A plush interior, super-smooth ride, decent power and seemingly the perfect size always put GM’s SUV at the top of our list. With no experience in the latest generation of the full-size SUV, we were eager to get our hands on one. However it was not to see if GM had refined what used to be their bread and butter even further. We had heard of wild rumors of the big SUV returning MPG numbers in the low 20’s. Could this even be possible? We grabbed a 2008 GMC Yukon and hit the road to find out.

At the heart of the fuel-efficiency rumors is GMC’s Active Fuel Management system. Simple in theory, the system deactivates cylinders when not needed essentially turning the 5.3L V-8 into a four-cylinder. It is not exactly a new technology and has been around in similar form on the Corvette helping it to achieve 26 MPG on the highway while still putting out plenty of horsepower.

Only recently (and just in time) has it been applied to GM’s full-size trucks and SUV’s. Looking at the Yukon’s EPA rating numbers of 14 city and 19 highway, it is easy to see the system is effective in theory.

Big 20-inch wheels may look bling but 55-series street treads were seriously out of their element in the dirt.

More interested in real world numbers from the Active Fuel Management system we put over a 1,000 miles of testing on our Yukon while it was in our greedy little hands. Our first tank, which was a mix of city and highway driving, produced only 14.5 mpg. On the long freeway drone out to our off-road test area and back our mileage increased slightly to 16.4 mpg.

Knowing that the off-roading we did dragged our numbers down we decided to head out on a road trip and made our way from our sunny Southern California global headquarters to San Francisco. On the way up on the most boring road in the world (the long and straight 5 Freeway) we encountered heavy winds and the result was only 16.6 mpg. To keep ourselves from going insane on the way back we took the much more interesting Highway 101 and without winds netted a more impressive 18.8 mpg.

While short of the 22 mpg rumors we have heard, the Active Fuel Management system does work and provide a bump in mileage. It is seamless and completely unobtrusive to the driver. There are no strange sounds, loss of power, shuddering or anything else to cue the driver that it is even present and operating. Without nursing it we were able to get 18.8 on long, flat freeway driving. Not bad for a big, honkin’ SUV but only expect similar numbers if you live in a fairly flat area and do a lot of highway driving.  

The rest of the Yukon takes upon what the previous generation was known for and builds upon it even further. The new interior is gorgeous, extremely comfortable and quiet making it the perfect vehicle for long road trips. Leather appointed seats with a host adjustments kept us comfortable for the six-hour drive to the Bay area. Overall the interior has a very upscale look and feel to it.

This is about max flex for the GMC Yukon. Without much articulation or traction, it is not a stellar performer in the dirt.

Our only gripes were the third row seat is useless for anyone except possibly Hobbits and there is no dead pedal leaving our left foot with no support on longer trips. The seats, while extremely plush and comfortable are also not that supportive. However leg room is generous for the second row and, with the third row removed, there is a decent amount of cargo room.

Adding to the comfort of the interior is the Yukon’s extremely smooth ride. On the very rough city streets that are part of our regular commute thanks to California’s budget cuts, the Yukon absorbed the massive potholes and broken pavement with little fuss. In fact, it is the smoothest riding SUV that we have yet to test. On the highway, that smooth ride continues with the Yukon riding like a luxury car. Adding to the luxury car feel is the interior is a quiet place well insulated from road and wind noise.

The Yukon's interior is fairly plush and everything is in the right place making it a comfortable place to spend time on our long road trip.	The third row has zero leg room making it suitable only for midgets or people you don't like.

While the soft suspension values of the Yukon yield an amazingly smooth ride, it also provides some sub-par handling. The Yukon does not wallow around corners like a drunken sailor but it does not inspire a lot of confidence for those that like to go fast or even at a moderate pace through the twisties. There is a bit of body roll and overall lack of a firmly being planted in the corner. Somewhat numb and over-assisted steering that provides little feedback also adds to this feel. Then again 5,600 lb SUV’s are usually not known for their cornering prowess anyways. We would rather take the buttery smooth ride than a bump in spring rate to make the Yukon better in the corners.

Once the pavements ended, things got somewhat ugly for our Yukon. Shod with 20-inch wheels, limited articulation, low-profile tires, big running boards, no traction aids and not a lot of height we didn’t expect much from the Yukon. In rough terrain the Yukon was either dragging a running board or stuck with one wheel hopelessly spinning in the air. It wasn’t much of a shock when the 20-inch street tires that came on it didn’t deliver any traction either. We ran out of articulation, tire and traction very rapidly cutting short our off-road testing.

The 5.3L V-8 provides 320 horsepower and 340 lb-ft of torque and returned a high of 18.8 mpg.

One area the Yukon did shine off-road was on high-speed fire roads. With its softer suspension the Yukon excels at absorbing smaller bumps and grading commonly found on faster dirt roads. Surprisingly, the suspension also bottoms out very smoothly. There is no teeth shattering jarring when the Yukon runs out of travel and this kept our spines intact when driving too aggressively.

The Yukon is a luxury car wrapped in the body of a four-wheel drive SUV. While it is not the most capable in the dirt, it still provides the benefits of four-wheel drive and can go where the majority of its owners will take it whether on or off-road. All while providing plenty of comfort in a very nice package.

We have always claimed if we had to pick a full-size SUV to drive across the country it would be the Tahoe. The refinements of the latest generation Tahoe and its bump in gas mileage make it even easier to select the Tahoe as one of our favorites for long road trips. With dealers now aggressively trying to dump full-size SUV’s in favor of more fuel efficient cars, now is actually a great time to buy a Tahoe if you actually need one.