GMC Yukon Hybrid

The GMC Yukon Hybrid – and its counterpart the Chevy Tahoe Hybrid –were the first vehicles to utilize the advanced two-mode hybrid powertrain developed jointly by General Motors, BMW and the then DaimlerChrysler. This full-size SUV launched a new breed of larger vehicles that are significantly greener than their gas-powered versions. 

Available with either two- or four-wheel drive, there are two trim levels available. The base Yukon Hybrid has a starting price of $51,610 for the 2WD model; $54,420 for the 4WD. The lavishly appointed Yukon Denali Hybrid 2WD starts at $58,925; the 4WD at $61,770. Other than an updated touch-screen navigation radio that includes a USB port and the ability to record broadcast audio, there are no changes to the Yukon Hybrid for model year 2012.

Powertrain

The core of the Tahoe Hybrid’s powertrain is GM’s 6-liter Vortec V8 with cylinder deactivation technology. In other words, this engine can shut down four of its eight cylinders when the additional power is not needed. That saves fuel. Beyond the engine, there’s a 300-volt battery that hides below the second-row seats. The vehicle’s two electric motors are housed within the transmission.

In order to keep the vehicle running at peak efficiency, this hybrid system is able to run in one of two separate modes – hence the name “two-mode hybrid.” For low-speed, low-impact driving, the powertrain works just like other hybrids; it stops the gasoline engine whenever possible so that it may draw power from one or both of the electric motors. The second mode is mostly for highway driving, at which time one or both electric motors can run concurrently along with the V8 engine in order to provide a power boost. The two-mode transmission is the key to the whole system, which attempts to keep the engine running at the optimum rpm for low fuel consumption. Essentially, it manages a balancing act between the engine and the electric motors. It is also responsible for making the transitions between the two modes practically seamless.

All of this technology results in a 25-percent improvement in overall fuel economy over the Yukon hybrid’s gas-powered counterpart. More impressive is a 40-percent improvement in city driving. Both the Yukon Hybrid two- and four-wheel drive models have an EPA rating of 20 city/23 highway/21 combined as compared to the conventional Yukon’s 14/18/16 with the 6.2-liter V8. Unbelievably, this huge SUV’s city fuel economy is 3 mpg better than a Honda Accord coupe with V6 engine and manual transmission.

Despite its focus on fuel-efficiency, the Yukon Hybrid still delivers all the power and capability needed from a full-size SUV. It boasts 332 horsepower, and can tow up to 6,200 pounds. Its four-wheel drive system is comparable to most trail-rated pickup trucks, allowing the Tahoe Hybrid to drive off-road or through difficult road conditions with excellent traction and stability.

Driving Impressions

From a stop, the electric drive can power the Yukon up to about 30 mph and some practice with the accelerator pedal can keep the big SUV under electric power for a couple of miles or so before the gas engine takes over. The transition from electric to gas power is silky smooth and once underway the ride comfort is exceptionally good for a vehicle this size. Steering feel is on the mark, and while body roll is present during an aggressive turn, it’s less than you would expect from a three-ton vehicle.
I’m impressed with the cylinder deactivation as a tool for increasing fuel economy. With a little practice, the big V8 can be coaxed into operating on four cylinders at around 40 mph, and can do so for several miles. On the Interstate it’s not difficult to maintain four-cylinder operation at 70 mph.