It's no secret that General Motors is lacking in the hybrid department. While import makers like Honda and Toyota score sales successes with strong-sellers like the Honda Civic hybrid and Toyota Prius hybrid, GM has focused its alternative-fuel technology efforts on the gasoline-ethanol blend of fuel, E85, and fuel-saving cylinder deactivation technology like Active Fuel Management.

Despite the fact that GM is leading the auto industry's E85 bandwagon, its efforts have been meager in the hybrid arena--until now. A new year means a new alternative-fuel strategy for GM and a lineup full of gasoline-electric hybrid models using a new two-mode hybrid system and an updated version of its mild hybrid powertrain.

"We are delivering on our promise to continue our steady rollout of additional hybrid applications, each offering different levels of affordability, fuel savings, and performance," said Tom Stephens, GM Group Vice President of Powertrain.

GM's first foray into hybrid technology for passenger cars was in 2005 with the Chevrolet Silverado hybrid. It features two accessory outlets powered by an electric motor (left) and automatically shuts off at a stop.

Starting with the 2007 model year, General Motors plans to debut several new hybrid cars and trucks equipped with one of two hybrid powertrains: the mild hybrid system found in a few vehicles today, and the real deal: GM's new two-mode hybrid powertrain. During the next couple of years, the automaker hopes to have 12 hybrid vehicles on dealer lots and more finite plans to take electric propulsion technology one-step further with a plug-in electric vehicle.

"Mild Hybrids"
GM calls vehicles that are assisted by electric motors but cannot run solely on electric power, "mild hybrids." While the automaker admits gas savings don't measure up to what's conserved by import hybrids, it argues that these milder hybrids still help save fuel, and do it costing much less than Toyota and Honda's hybrid powertrains.

In model-year 2005, Chevrolet launched what it calls the world's first hybrid pickup truck, a green version of the Silverado 1500. The truck's 5.3-liter V8 automatically shuts off at stoplights, resulting in a 10-percent fuel-economy gain. This is a hybrid in name only, as its electric motor did not help propel the vehicle. It only serves to re-start the engine when the driver pushes on the gas pedal. Once the gas engine is running, the electric motor turns into a 2400-watt generator that supplies 110-volt AC (household) current to outlets under the rear seat and in the cargo bed.

For '07, GM's mild hybrid system was improved in the Saturn Vue Green Line. The Vue Green Line compact SUV uses a 2.4-liter 4-cylinder engine joined by a battery-powered electric motor to make 170 horsepower. As with Silverado, Vue can't run on electric power alone and saves gas by shutting off at stoplights. However, it does one better than the Silverado Hybrid in that the electric motor helps power the vehicle during initial acceleration. Consumer Guide's test 2WD Vue V6 averaged 21.6 mpg, and test Green Lines averaged about 27 miles per gallon.

Toyota Camry and Honda Accord's new challenger, the midsize Saturn Aura hybrid, debuts in spring as General Motors' first hybrid car. Using the same powertrain as the Vue Green Line, GM claims the '07 Aura Green Line will deliver 25 percent better fuel economy than the V6-powered Aura XE.

Saturn's Green Lines

Top: 2007 Saturn Aura Green Line. Bottom: 2008 Saturn Vue Green Line

"Two-Mode" Hybrid System
Like a "mild hybrid," the fully hybrid two-mode system shuts the engine off at a stop and aids in restarting, but also allows the driver to operate the vehicle in full electric mode during low speeds. General Motors collaborated on its two-mode system with DaimlerChrysler and BMW and will roll it out later this year for the 2008 model year. "GM is taking some advanced technologies and rolling them out in relevant vehicles," Stephens said.

It uses a special transmission with four gears and two continuously variable modes and a 300-volt nickel-metal hydride battery pack to run a pair of electric motors. The system allows the vehicle to operate in two modes depending on speeds and driving conditions.

The first mode is used for low-speed driving and allows the vehicle to operate using just the electric motor, just the gas engine, or a combination of both. The most fuel is saved during low-speed, stop-and-go traffic because the car has the ability to run without ever engaging the gas-powered engine. The second mode is used during high-speed highway driving and/or towing. The electric motor is used to assist the gas engine, especially when more power is needed for highway passing and towing. The combustion engine is always running in this mode.

Two-mode will show up first on GM's full-size SUVs, 2WD versions of the 2008 Chevrolet Tahoe and GMC Yukon, followed by the redesigned 2008 Saturn Vue Green Line. The Yukon and Tahoe applications will use a 5.3-liter V8 engine and improve fuel-economy around 25 percent versus non-two-mode V8 models.

In Vue, it will be applied to a 3.6-liter V6 engine and GM claims drivers will see a 45 percent fuel-economy gain over non-two-mode equipped V6 models. Four-cylinder Vue Green Lines will still use the previous mild-hybrid system found on '07 versions.

"General Motors is serious about fuel economy and minimizing the environmental impact of our products. We are introducing this two-mode system where it will have the most impact--in the full-size SUV class," said Lisa Hutchinson, Saturn's Brand and Product Development Director.

Who Resurrected the Electric Car?
For most, the words GM and electric car conjure up images of EV1, GM's doomed, but loved battery-powered car. General Motors is at it again, however. Unveiled at the 2007 Detroit Auto Show, the automaker gave show-goers a peek into the electric car future when it took the wraps off of the Chevrolet Volt concept.

GM's new plug-in electric car concept, the Chevrolet Volt, was unveiled at the 2007 Detroit Auto Show.

The 4-door concept uses an electric propulsion system GM calls E-Flex. It gets power from the combination of a gas-powered engine and an electric motor powered by a lithium-ion battery pack. What makes this car different from a hybrid is that it has the ability to run solely on electric power for 40 miles, even at highway speeds. Even bigger news is that an outlet in your garage or the car's gasoline-powered engine is how the battery gets recharged. The 1.0-liter 3-cylinder turbocharged gas engine kicks in only to charge the battery and cannot drive the car's wheels. What's more, Volt's battery pack doesn't have to be coupled strictly with a gasoline-powered engine. GM says Volt can also use an E85, hydrogen fuel-cell, or diesel-powered engine.

A vehicle closer to production reality is a plug-in version of the Saturn Vue Green Line. Green Line will combine the use of a modified version of the 2008 Green Line's two-mode system and a lithium-ion battery pack charged by a household outlet. Saturn estimates that the plug-in Vue will be able to travel in excess of 10 continual miles solely on electric power, even at highway speeds.

GM is serious about becoming a true hybrid contender in the marketplace, and will roll out a hybrid portfolio that will rival any other maker's current gasoline-electric offerings. During the next two years, GM will apply fuel-sipping two-mode technology to transform its thirstiest trucks like the Cadillac Escalade, Chevrolet Silverado, and GMC Sierra into lean green machines. And with GM's foray into electric propulsion technology with Volt and Vue, don't be surprised if "filling up" at your garage's power outlet becomes more important than topping off the tank at the gas station.