When it comes to trucks, numbers matter, arguably more than they do with cars. The Yukon’s flex-fuel 5.3-liter V8 delivers 320 horsepower and 335 pound-feet of torque, and most Yukons weight in the mid-5000-pound range where lots of torque is welcome.
For the most power you need a Denali and its 6.2-liter V8: 403 hp and 417 lb-ft of torque. This powerhouse gets the Denali moving with ease, delivering very similar power-to-weight as the Sequoia. The Denali's tow rating is 100 to 300 pounds less than other Yukons and it is not available with a 4WD system that has low-range gearing.
Both V-8s have a system to shut off half the cylinders when not needed, a condition that exists under power infrequently in big trucks. Yukon EPA ratings typically run 14 city/19-20 highway with the XFE 2WD version rating 15/21, in the same neighborhood as the Expedition. The considerably more powerful Denali is in the 12-13/18-20 range, much like the similarly powered Toyota Sequoia and Infiniti QX56. Recent EPA ratings are less optimistic than they used to be, but any way you look at it, you're going to use lots of gas.
The Hybrid Yukon offers big gains in city fuel economy, netting EPA numbers of 21/22 for 2- or 4-wheel drive. Real-world drives show EPA numbers for hybrids remain on the optimistic side. In back-to-back drives between hybrid and standard GM SUV's we found the standard (lighter) truck just edged the hybrid on highway fuel economy while the hybrid was better in urban environs, getting around 17 mpg versus the 5.3 around 13 mpg. EPA diesel numbers on the other hand skew pessimistic, with Mercedes' GL and ML350 VW's Touareg, Audi’s Q7 and BMW X5 diesel all in the 17-19/23-26 range and easily matched.
The numbers game continues with tow ratings. Yukon ratings aren't quite as high as Expedition and Armada, and 1500 pounds below the Sequoia's top 10,000-pound rating. To find real towing ability you need to know the trucks' GCWR and subtract the truck (and all passengers/cargo) from it. For example, a Yukon rated to tow 8200 pounds max might pull only 6700 pounds with the truck loaded; VW's Touareg diesel is rated at 7716 pounds, but that is with the vehicle loaded.
Driving a Yukon is pleasant. Power comes on smoothly, with no surges or hiccups, and it is accompanied by a pleasant tone that reminds us of classic dual exhaust. Transitions effected by the fuel-management system are invisible, with the only indication a telltale in the information display in the tachometer. The six-speed automatic sorts out gears well. It has a manual shift function managed by a rocker switch in the handgrip on the column shift lever that rev-matches downshifts, but unlike most competitors you must first move the lever to M.
The Hybrid works seamlessly and doesn't require any new driver action, just some familiarity with the different noise and, for maximum efficiency, driving style. At very low speeds propulsion is by electric power only, and you have to watch for people walking out in front of you in parking lots since there is only tire noise and some whirring when you start or stop. The system will do 30 mph on electric alone in ideal circumstances but in most cases the gas engine is on by 10 mph. It usually shuts off the gas engine when the vehicle is stationary and the majority of time your foot is on the gas pedal it is a combination of the gas engine and electric motors powering you.
If you step on the gas hard as you might to get across a busy street there is a moment, some fraction of a second, before the gas engine starts and the system delivers its full 367 lb-ft of torque, so you should try that in the open a couple of times to know exactly how the truck will respond. There's enough power to get the Hybrid (and a 4000-6000 pound trailer) going easily, though it may sound odd at first as the gas engine goes to a certain rpm and stays there while the truck catches up with it. The brakes in a Hybrid will feel touchy at first because they signal regeneration, which adds more retarding without any change in brake pedal pressure.
Driving Yukon models along twisty, two-lane roads on both coasts we found they tracked well through sweeping bends traversed well above the marked 40-mph advisories. Like all large truck-based SUVs, steering is still somewhat slow, but it is precise and offers good feedback and a decent turning circle by truck standards. The handling is also sharper than in the previous generation, due to a stronger and stiffer frame; coil-over-shock independent front suspension; revised, multi-link, live axle rear suspension; and a wider track, by some three inches in front and an inch in the rear. Still, the Yukon is a full-size truck and is prone to body lean in turns and slow reactions in quick changes of direction.
We found the ride to be comfortable and controlled on South Carolina freeways, some of which were glass-smooth while others were buckled from severe winters. With the Denali's available 20-inch wheels, the suspension didn't jolt but you can tell those are heavy truck parts underneath, even on Chicago's notoriously pockmarked streets. The turning circle impressed us. It takes less space to make a U-turn in a Yukon than it does in other SUVs in this class; even some relatively small vehicles such as the Mitsubishi Eclipse need more space to turn around than the Yukon. This is helpful in a world of big SUVs and compact parking spaces. The brake pedal was solid and firm, with a prompt and confident response.
Abundant sound deadening material mutes road noise; you'll hear some from the rear tires only if the stereo is off. That the stereo has to be on for the navigation system to operate is irritating, a strategy shared with expensive Mercedes vehicles. We like that GM vehicles now provide off switches for the daytime running lights and for the inside rearview mirror's auto-dim function.
The 2010 Yukon all-wheel drive models use a single-speed transfer case. If you want a 4WD with low-range gearing, as you might for steep slippery launch ramps or ski resort access, or to tow the Yukon as a “dinghy” behind a motorhome, you have to get an all-wheel drive model with the optional two-speed transfer case. Hybrids have low-range gearing but check with your dealer about towing one as a dinghy.
The available brake controller for trailers with electric brakes (it obviously won't work with surge brakes and may not be compatible with electro-hydraulic disc systems) integrates the brakes on both vehicles for the smoothest, most effective action.