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 Al Gore guilt trips and astronomical Chevron bills - the 2-Mode hybrid. Its first application is in the Chevy Tahoe and GMC Yukon.

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 20 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 6.0 liter V8 also runs on four 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 (22mpg) 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 in the summer of ’08. The Silverado and Sierra pickups are next. It’s scalable so Saturn Vue will also get 2 Mode to compliment the “mild hybrid” that already exists. Also, Chrysler and BMW are partners with GM and they will create their own hybrids with the EVT.  

This all means nothing if the system doesn’t work well. During my very short drive with a preproduction GMC Yukon, the 2-Mode performs admirably. 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 whines 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.

Other than the initial electric roll-away 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. 

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. Sorry, the large promotional decals that scream Hybrid! on this tester are not part of the package. GM understands that some owners might want them though, and are actually considering making them available at the dealership. Feel free to put them next to the “My Labrador is smarter than your honor student” bumper sticker.

These vehicles are not going to turn tree-huggers into truck-huggers. They are large vehicles that consume a lot of resources just by being built. GM has endured some 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 21 with the hybrid and that driver consumes 357 fewer gallons of gas. That’s over $1,000 a year with fuel conservatively priced at $3 a gallon. 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. On sale in the first quarter of 2008, these hybrids have list prices that hover around the $50,000 mark. There’s a $1,900 government tax credit to soften that blow. These hybrid twins occupy a unique niche in the market. The only other gas/electric vehicle that carries more than five is the smaller Highlander (at $37,495 when equipped to seat seven) and it’s towing is limited to 3,500 pounds. In the end it’s the marketplace that will decide if Chevy and GMC are wise to offer up a low-guilt sport ute. The technology is impressive and I hope to get a tester for a full shake-down soon.  Time will tell if truck buyers are in the mood for 2-Mode, but tech lovers will find it, well, electrifying.