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About the
2008 Chevy Tahoe and GMC Yukon
 

General Motors will introduce the Chevy Tahoe and GMC Yukon models as hybrids in 2008. Fuel economy improvements of at least 25% are expected.

This will use GM's new "two-mode" system. This system will be jointly used by GM and Chrysler. The two companies hope that by working together in developing this system, they will have a strong competitive position in the hybrid market. The system is referred to by GM as Advanced Hybrid System 2. While existing hybrid designs offer their greatest fuel economy improvements at low speeds, GM claims their design will be able to maximize efficiency at highway speeds.

The system uses two electric motors instead of one. One is used at speeds up to about 40 mph, then the second motor comes into play. The design is said to be particularly good at giving optimum power for pulling a trailer.

GM's strategy focuses on first bringing out their larger models as hybrids first. "We decided we would go after hybrids attacking the highest fuel-consuming vehicles first because that's where we could save the most petroleum," said Tom Stephens, group vice president in charge of GM's power train operations.

The vehicles will have two 60 kW electric motors. The battery pack will operate at 300 volts. GM will use displacement on demand to enhance fuel economy. A few engine "tweaks" will be used, including cam phasing, late-intake valve closure and a very high compression ratio. The engine will be a Vortec V8. As a point of comparison, the 2006 Tahoe with the 5.3 liter V8 and 4WD, is EPA rated at 15 city / 19 highway.

May 2005, corrections Aug. 2007