Video: Driving Northwest: The GMC Yukon 2 Mode Hybrid

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Americans covet full-sized SUVs for so many reasons. They carry lots of people, they're not minivans, they tow heavy loads, they're not minivans, they swallow enormous amounts of cargo and they're not minivans. Buyers feel safe and stylish in sport utes, probably because they're not, well … you know. Lately, talk about global warming has made dropping junior off at soccer practice in a school bus-sized vehicle a bit gauche. GM thinks it has the answer to both to Al Gore guilt trips and astronomical Chevron bills - the 2-Mode hybrid.

First, a reality check. Those who are thinking "Wow! Hybrid! A honkin' big truck that gets 40 mpg" might want to consult their physics textbooks on the way to dreamland. These are full-sized SUV trucks that tow up to 6,200 pounds. The last GMC Yukon Denali I tested returned 14 miles per gallon in mostly highway driving. GM's new uber hybrids score 22 highway/21 city on the new more realistic 2008 EPA ratings. A Prius it ain't but the increase in fuel economy is admirable. GM is quick to point out that this truck gets the same city mileage as a 4-cylinder Toyota Camry. 

To understand GM's 2-Mode hybrid, let's check in with "Hybrid Systems For Dummies" and look at the most popular system on today's market, Toyota's Hybrid Synergy Drive. Simply put, it has two propulsion sources - a gas engine and electric motors. With Synergy Drive, the engine, motors and transmission (called a "power split device" here) are separate but work together. The vehicle starts out silently using only the electric motors until it reaches a certain speed (I generally find it to be around 20 mph) or the driver floors the accelerator. At that point the gas engine smoothly kicks in to offer up the required horsepower. The switch between power sources is managed by the sophisticated power split device. At around 35 miles per hour Toyota's system largely becomes a gas powered vehicle, the electric propulsion side offers very little assist. Battery packs are charged by the motors that become generators when the car is coasting or braking. At a stop the gas engine shuts down to save gas. Hybrid Synergy Drive is tailored specifically to each platform. Prius is different from Highlander which is different from LS600Lh.

GM's 2-Mode also has a gas engine, electric motors and battery packs. However, the packaging is quite different. The two electric motors are built into the transmission case (called an Electrically Variable Transmission or EVT). One motor is where the torque converter would normally be. The second (that's also a generator) is behind a set of four fixed gears. Mode 1 is the dynamic you'd expect when driving Toyota's system. It moves from a stop silently on electric power so you can creep up and scare neighbors and it shuts down automatically at stoplights. At higher speeds you enter Mode 2. Here the electric motors' oomph constantly keeps the gas engine in its optimal efficiency band. The 332 hp 6.0 liter V8 also runs on 4 cylinders and Mode 2 keeps the engine running in gas-saving operation twice as long at cruising speeds. Unlike other hybrids, 2-Mode gets better fuel economy on the highway than city. 

Tech geeks take note: The 2-Mode's HOS or Hybrid Operating System looks at conditions every 100 ms to determine how to adjust the system for optimal efficiency. It also figures out if you're towing a heavy load and takes the electric motors out of the action. These rigs can tow 6,200 pounds for the rear-drive model, 6,000 when outfitted with 4-wheel drive.

In essence the elegant modular approach with motors in the transmission allows GM to create new hybrid models by adding an engine and battery packs to the EVT. Cadillac Escalade will get 2-Mode this fall. The Silverado and Sierra pickups are next. It's scalable so Saturn Vue will also get 2 Mode to complement the "mild hybrid" that already exists. Also, Chrysler, Mercedes and BMW are partners with GM and they will create their own hybrids with the EVT (watch soon for my review of the Dodge Durango hybrid).  

This all means nothing if the system doesn't work well. During my week with the GMC Yukon, the 2-Mode performs admirably. Paying close attention to fuel economy, I'm seeing 19 mpg in city slogging and 22 during highway cruising. The easy description is that it feels like driving a really big Prius. Pulling away silently on electric power, it stays in electric-only operation longer than expected. The experience of a big SUV gliding away with only the faintest of electric whine is a very eerie experience, like Jack Black performing a perfect gymnastic routine. It's difficult to tell when the V8 fires up, it's that smooth. A small gauge display informs drivers when the gas engine enters V4 mode, otherwise they'd never know. The large LCD display in the center stack shows the power and charging activity. It's is very similar to Toyota's.

KING

Yukon hybrids carry a $5,000 premium over the standard rig with a list price that starts at $51,000.

Other than the initial electric roll away, some faint electric whine and the engine shutting down at stop lights, the driving dynamic is very much like any GMT900 SUV. Good thing because GM utes are my top pick when it comes to full sized utes. Batteries are under the mid row seats. Like all GM SUVs, the third row does not fold flat into the floor. Either fold it forward or remove it to increase cargo space. Another gripe? The steering wheel does not telescope.

The extra weight from the 2-Mode components is offset somewhat by using aluminum components and thinner seats. There are also aerodynamic tweaks to the front fascia, running boards, alloy wheels and liftgate. GM is going for the hybrid halo and has swaddled this ute with huge graphics to inform the unenlightened that you are sincerely trying to save the planet with your large SUV.  They look good next to a "My Labrador is smarter than your honor student" bumper sticker.

Will these vehicles turn tree-huggers into truck-huggers? Hardly. They are large vehicles that consume a lot of resources just by being built. GM has endured criticism that they did not build a high mileage Prius-like vehicle, they've just come up with another hulking SUV for Mother Earth to endure. To this end The General offers up the 2010 Chevy Volt and this math: Take a car that normally gets 30 miles to the gallon and raise it to 40 and the average Joe and Jane that drives 15,000 miles a year saves 125 gallons of gas. Do the same with a standard Yukon rated by the EPA at 14 mpg in the city, raise it to 20 with the hybrid and that driver consumes 348 fewer gallons of liquefied dinosaur fossils. Today I saw gas at $3.80 a gallon and that means a yearly savings of over $1,300. These figures are certainly fluid but shed light on GM's strategy. Let's not forget, buyers demand full-sized SUVs to haul large amounts of people, cargo, and to tow heavy loads. These are things that can't be done with a Prius.  

Folks won't go green if it requires too much green. Yukon hybrids carry a $5,000 premium over the standard rig with a list price that starts at $51,000. There's a $1,900 government tax credit to soften that blow. The only other gas/electric vehicle that carries more than 5 is the smaller Highlander (at $37,495 when equipped to seat 7) and it's towing is limited to 3,500 pounds. In the end it's the market place that will decide if GMC (plus the Chevy and Caddy cohorts) are wise to offer up a low guilt sport ute. The technology is impressive, but these days the stigma of driving a large ute is a big deterrent. Time will tell if truck buyers are in the mood for 2-Mode but tech lovers will find it, well, electrifying.