First Tests

2009 GMC Yukon 2 Mode Hybrid First Test

Green Giant: Big technology in a Big SUV (with big stickers) may not be enough

Green Giant: Big technology in a Big SUV (with big stickers) may not be enough

Although they’d never admit it, the folks at GM learned a thing or two from Toyota. Not only did the Prius give Toyota a “greener” public image, it did a good job with the technology, too. Now, it’s GMs turn to shine. We recently got some time behind the wheel of a 2009 GMC Yukon 2-Mode Hybrid (on sale now, along with the Chevy Tahoe Hybrid) to see how it compares with a non-hybrid model. After just finishing up a 12-month, 20,000-mile tour of duty with a comparably equipped GMC Yukon SLT2 non-hybrid model, we can say the new 2-Mode system (co-developed by DaimlerChrysler, BMW, and GM) is nothing short of stunning. In large-SUV history, this just might be the single greatest leap forward in powertrain technology. So why does GM want to put such an impressive piece of technology in such an unpopular vehicle? The answer, says GM group V.P. of powertrains Tom Stephens, is simple: “This choice highlights our commitment to save as much fuel as possible by applying our best technology to the highest fuel-consuming vehicles first.”

Whether GM’s become a better corporate citizen remains to be seen, but given this is a fuel-gulping 5600-pound sled, the results are impressive. Recently released EPA fuel-economy numbers don’t look stellar at 21-mpg city/22-mpg highway, but that’s a huge jump up from a non-hybrid. Our comparably equipped long-term 5.3-liter V-8 GMC Yukon averaged 13.9 mpg combined (around 12 mpg city/ 18 highway). The same city routes in our Yukon 2-Mode Hybrid yielded 17.7 mpg with a combined average of 18.2 mpg over three tankfuls. In a world where O.E. designers and engineers are slashing and clawing for a fraction of a percentage point to improve fuel economy, a year-to-year jump over 30 percent (combined) is impressive. How does the system work?

At the heart of the 2-Mode system is the electronic variable transmission (EVT), which uses two 60kW electric motors that allow continuously variable operation at high and low speeds. Additionally, there are four fixed gears that also can act as a normal automatic when needed. Both are controlled by a computer with a sole purpose of making sure systems work together to provide the maximum operating efficiency based on vehicle load and driving conditions. Power for the two EVT electric motors comes from a 300-volt nickel-metal hydride energy-storage system, located under the second-row seats (which can flip and fold forward, though not electronically). The batteries are primarily charged during regenerative braking, but also can be charged while cruising. The hybrid powertrain uses the standard all-aluminum 6.0-liter Gen IV V-8 gas engine with active fuel management, which employs a new late-intake valve-closing technology, allowing the engine to run in V-4 mode longer and shut off sooner when coming to a full stop. Full electric takeoffs (depending on how you accelerate, up to 25 or 30 mph) are smooth and silent. Engine startups and shut-downs are noticeable but not intrusive, though getting used to the dead quiet at stop signs or traffic lights will take some time. (Now if only the Hybrid sticker packages-too many in too many places-were as seamless and subtle as the powertrain operation.)

The Gen IV all-aluminum 6.0-liter V-8 and four fixed gears (slotted through the two electric motors) makes this the most powerful hybrid sold in the U.S.

GM included two separate readout strategies to provide the driver with instantaneous information: one analog gauge, one computer screen. The economy gauge teaches the driver (swinging needle) how to use the most efficient braking and accelerating techniques (in a nutshell, extreme smoothness rules the day). Similarly, a dedicated “Hybrid” readout on the nav screen identifies where the power is coming from (battery or engine) and where it’s going (wheels or battery). Both are simple and easy to use.

Also included with this technology are a host of exterior changes designed to improve aerodynamics. Gone are the foglamp and tow-hook openings. The grille is slightly larger for better cooling. The roof rack rails are eliminated for less drag. Runningboards are tapered front and rear to decrease wind resistance. The previous round body shape was given sharper cuts to hold air, more shapely rear taillights cut through wind better, and a longer and wider front air dam moves more air underneath.

Subtle differences between hybrid (left) and non-hybrid (right) Yukons. Note absence of foglights and flush bumpers.

Likewise, GM engineers wanted to remove as much mass from the vehicle as possible. Outside, a new aluminum hood and liftgate replaces the steel units. A fixed rear glass gate saves weight as well as does the complete removal of a spare tire and jack. Thinner-profile front seats save 10 pounds each and give second-row passengers 1.5 inches of added knee room. Aluminum wheels, a slightly smaller fuel tank, and a 42-volt power steering unit also help save weight.

Perhaps more impressive than any of these details, especially to the bigger families and weekend warriors who gravitate to vehicles of this size, our GMC Yukon 2-Mode Hybrid sacrifices little towing, payload capability, or passenger space. The Yukon still can carry up to eight people, tow a 6100-pound boat, and tote more than 1400 pounds of gear. And at the track, the system, with a slightly larger engine, proved faster in almost every way. We’re usually skeptical when it comes to “no-compromise” solutions, but after driving this fuel-efficient full-size SUV, it looks as close as it gets. GM knows this is a long-term investment so it’s willing to keep costs reasonable for now (some speculate GM is subsidizing between $8000 and $10,000 per vehicle), with the hope that the same windfall that blew over Toyota with Prius, might happen for the General. In the meantime, 2WD Yukon Hybrids will start at $50,945, with 4WD models $2810 more.

Cadillac‘s Escalade 2-mode hybrid

With all the attention on the Chevy Tahoe and GMC Yukon 2-Mode Hybrids going on sale in January, some might wonder where the Cadillac Escalade is in all this. Isn’t it supposed to be the technology leader within GM? Although Cadillac says the Escalade was part of this rollout plan from the beginning, it won’t be getting this hybrid system until the summer, almost six months after Chevy and GMC. But don’t expect to find any of the same aero, body, or physical changes on the Cadillac that are part of its Chevy and GMC brothers. Cadillac says it’s not about compromise, so the Escalade will keep its full-size spare, steel rear hatch, glass release, and standard hood as well as all those cushy interior seats. However, it’ll most likely carry the bigger premium price-tag Cadillac buyers will be more willing to pay. There seems to be something about this luxury class that loves being environmentally friendly. No word yet on pricing, but we’d expect Escalade 2-Mode Hybrids to start around $60,000.

2009 GMC Yukon 2WD Hybrid
Base Price $50,945
Price As Tested $51,790
Vehicle Layout Front engine, 2WD, 7-pass, 4-door SUV
Engine 6.0L/332-hp/367-lb-ft OHV 16-valve V-8 plus 2 81-hp/184-lb-ft electric motors
Transmission 2-mode CVT/4-speed auto
Curb Weight 5659 lb
Wheelbase 116.0 in
Length x Width x Height 202.0 x 79.0 x 76.9 in
0-60 mph 8.3 sec
Quarter Mile 16.2 sec @ 87.8 mph
Braking, 60-0 mph 137 ft
Lateral Acceleration 0.65 g (avg)
MT Figure Eight 30.5 sec @ 0.52 g
EPA City/Hwy Econ 21/22 mpg
CO2 Emissions 0.95 lb/mile
On Sale In U.S. Currently