Monday, April 25, 2005

Al Golub / General Motors The hybrid powertrain installed in the buses is a larger-scale version of the system being developed for the automaker's full-size hybrid SUVs.

GM tests hybrid buses

Automaker will deliver the fuel-efficient vehicles to Yosemite to shuttle visitors around the park.

By Ed Garsten / The Detroit News

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General Motors Corp. plans to deliver a fleet of hybrid-diesel buses to majestic Yosemite National Park in California today in a move that will help the automaker bring full-size hybrid sport utility vehicles to market.

The hybrid buses run on both diesel fuel and electricity and will be used to shuttle visitors in and around Yosemite.

The hybrid powertrain installed in the buses built by Hayward, Calif.-based Gillig Corp., is a larger-scale version of GM's so-called two-mode system being developed for the automaker's full-size hybrid SUVs slated to go on sale in late 2007.

A two-mode hybrid system has a "dual personality" said Tim Grewe, GM's chief engineer of hybrid propulsion systems, where the vehicle relies primarily on the electric motor at low speeds and more on the internal combustion engine at higher speeds, as well as passing and climbing situations.

The pressure on GM to sell more fuel-efficient, less polluting vehicles has been mounting as fuel prices rise. Rivals Toyota Motor Co., Honda Motor Co. and Ford Motor Co. are already marketing hybrid cars and small SUVs.

While GM has no plans to accelerate the launch of hybrid versions of the Chevrolet Tahoe and GMC Yukon, lessons learned from the operation of the buses used around Yosemite Park and in 22 cities could help change those plans.

"There's interest in doing that, and essentially, the General Motors validation process is what's pacing that," said Grewe. "We really have to maintain quality before we put the new technology out there."

GM's flexibility in bringing hybrid-powered light trucks to market sooner is hampered by a decision to install the system on a new line of full-size SUVs that arrive next year, rather than on existing SUVs.

If GM could accelerate the introduction of the hybrids at all, it could make a big competitive difference, said Lindsey Brooke, an analyst with Farmington Hills consultants CSM Worldwide.

"Even if they were to introduce this (hybrid system), say, midyear as an '06 model, it would benefit the company," Brooke said, "because they're having to endure another two model years with Toyota spreading its hybrids in the market before they have a strong hybrid."

GM says the hybrid system that will power the Yosemite shuttle buses reduces certain emissions by up to 90 percent, offers 50 percent better acceleration than a conventional diesel bus engine and improves fuel economy by as much as 55 percent in diesel-hybrid commuter buses now operating in Seattle.

The two-mode hybrid version that will eventually go into consumer vehicles is being jointly developed by GM and DaimlerChrysler AG. The companies say it will improve fuel economy by at least 25 percent in light trucks.

Following GM's introduction of the hybrid Tahoe and Yukon, DaimlerChrysler's Chrysler will introduce a Dodge Durango powered by the same two-mode system.

You can reach Ed Garsten at (313) 223-3217 or egarsten@detnews.com.