January 9, 2005

GMC Graphyte Hybrid SUV concept offers "guilt-free performance"

Detroit, Michigan - Equipped with General Motors' latest two-mode full hybrid propulsion system, the GMC Graphyte concept vehicle is a 4X4 SUV with 25 percent improved fuel economy, announced the company. It was designed and built at the GM Advanced Studio in Coventry, England.

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The midsize Graphyte uses a two-mode full hybrid system combined with a Vortec 5300 V-8 with Displacement on Demand technology similar to the hybrid system that will be available on GMC Yukon and Chevy Tahoe full-size SUVs in 2007.

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

GM's two-mode full hybrid system has been established as the starting point for the GM-DaimlerChrysler collaboration. Variants planned include rear-, front- and all-wheel drive versions for cars, trucks and other vehicles.

The first mode provides fuel-saving capability in low-speed, stop-and-go driving - the kind of driving typical of urban commuting - with a combination of full electric propulsion and engine power. The second mode is used primarily at high speeds to optimize fuel economy, while providing full engine power when conditions demand it, such as trailer towing or climbing steep grades. It works with other technologies such as Displacement on Demand to reduce fuel consumption at highway speeds.

"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. "With the Graphyte, we've demonstrated its integration into a type of vehicle where its fuel-saving technology will do the most good, while maintaining all the utility for which GMC trucks and SUVs are known."

The Graphyte includes a 300-volt NiMH cross-vehicle battery pack located beneath the rear passenger seat and accessory systems under the hood to support the electrically driven HVAC, power steering and power brake systems. The drive system itself, including two compact electric motors and a series of gears that provide an infinite range of drive ratios, is contained within the case of a conventional Hydra-Matic 4L60-E automatic transmission.

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