GM Riding The Bus


    ANN ARBOR — While General Motors Corp. has pretty much left the hybrid passenger car market to Honda and Toyota, the domestic automaker hasn’t left the technology lying on the side of the road.

    GM executives have decided to focus the company’s hybrid efforts on larger vehicles. For instance, GMC unveiled a concept SUV called the Graphyte in January.

    The Graphyte is a four-wheel drive, midsize truck that mixes a two-mode full hybrid with a Vortec V-8. This system is similar to the one GM says it will make available in its full-size SUVs, the GMC Yukon and the Chevy Tahoe, in 2007.

    And the hybrid version pledges to improve the Yukon and Tahoe mileage by 25 percent.

    “The promise of the Graphyte’s hybrid technology is guilt-free performance. It provides a real and dramatic improvement in fuel economy without compromising the reasons customers want to use their SUV,” said Tom Stephens, group vice president of GM Powertrain.

    On an even bigger level, GM has hybrid-equipped buses operating in 18 cities across the country, including Seattle and Minneapolis, and in Indianapolis, which began running the buses in February. The hybrids deliver improved fuel economy and fewer emissions than standard diesel-powered buses. The bus also accelerates faster and runs quieter than its predecessor.

    So the automaker really believes that bigger is better, at least when it comes to hybrids.

    “GM feels it is best to employ hybrid technology first on large vehicles, such as buses and SUVs, because they generally are the largest consumers of fuel,” said Stephens.

    David Cole, of the Center for Automotive Research in Ann Arbor, said GM is not as aggressively involved in the hybrid market today as the company will be in a few years.

    “They have not concentrated their hybrid program on smaller vehicles. GM and DaimlerChrysler announced a joint venture a couple of months ago to develop a hybrid vehicle. But their concentration is actually on larger vehicles,” he said.

    Cole said GM’s thinking behind its hybrid plan is pretty straightforward.

    “If you’re going to get a 30 percent improvement in fuel economy with a hybrid, that 30 percent improvement in terms of dollars saved or gallons of fuel saved has a great deal more impact on light trucks than it would on small cars,” he said.

    The hybrid propulsion system in the Indianapolis transit buses uses electric motors and a 5.9-liter diesel engine. GM Allison Transmissions, Cummins Inc. and Remy International all had a hand in creating the system, while Gillig Corp. built the buses.

    “In a bus type of application, where these start and stop, they’re getting like 60 percent fuel economy improvement over the conventional buses. In those large vehicles, the fuel savings is just absolutely enormous,” said Cole.

    The real value of a hybrid is found on the streets and not on the highways. The hybrid doesn’t idle and burn fuel at a traffic light; it shuts down and regenerates itself by capturing the deceleration energy. That energy is then converted into electricity that gets stored in the battery and is the feature of a hybrid that improves fuel economy.

    Cole said driving a hybrid on a highway doesn’t return as dramatic savings because the stop-and-go found on city streets doesn’t exist — at least not normally — on the expressways.

    “That is one of the reasons why people have complained that they haven’t come close to what the EPA data says for the Prius hybrid or the Honda hybrid,” said Cole.

    The American Council for an Energy-Efficient Economy (ACEEE) recently released its list of the “greenest” vehicles in the country. Four were hybrids. Honda had the Insight and Civic Hybrid ranked second and fourth, respectively, while the Toyota Prius was third. The Ford Escape Hybrid was ranked 11th and was the first SUV to make the list.

    The greenest car ACEEE listed, though, wasn’t a hybrid. It was the Honda Civic GX that runs on compressed natural gas. The car’s mileage isn’t as high as the hybrids, but it has near-zero emissions and that impressed the council.

    “Ultimately, the only value the hybrid gives is capturing what we call the regenerative braking; it captures some of that energy. When you stop at a light, it shuts down. When it takes off, it instantly starts the engine and away you go,” said Cole.

    “It’s a wonderful technology. I’ve driven all of the hybrids and they’ve done a terrific job with them.”    

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