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The Chevrolet Tahoe Hybrid's bank of nickel-metal hydride (NiMH) batteries, located out of the way and under the second row of seats, forms the heart of the truck's Energy Storage System. Photos: General Motors Corp.
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Because the Chevrolet Silverado pickup truck has the same general configuration and dimensions as conventional vehicles — but boasts better fuel economy both in city and highway driving — it makes an ideal choice for fleet managers.
A DIFFERENT TYPE OF RIDE

No additional skills are needed to drive a hybrid, but there are new sensations to get used to. There's no separate starter motor to crank the engine; when starting, the electric motor engages the engine and, suddenly, it's running.

If already hot, the engine may not turn over when you turn the key. Ease down on the gas pedal and the SUV starts rolling on pure electric power. The engine stays off. To accelerate more quickly, step down harder and the engine turns on. A computer determines which source of power is best. For really quick starts, both forms of power are blended seamlessly and optimally.

Stepping on the brakes feels different in the Tahoe. The sophisticated regenerative braking system works in tandem with the hydraulic brakes. The system uses the SUV's energy, turning the motor into a generator. The electrical energy is stored in the NiMH batteries and is available when needed. A brake pedal emulator provides resistance in the pedal, so stopping feels almost the same as with conventional brakes. During my test drive, there was a noticeable clunk each time I stopped, but only when I began braking.

One way to save fuel is to shut off the engine. That's what Auto Stop does when the engine is warm and you stop. Restarting is electric up to 30 mph, then the V-8 kicks in. When loafing along on level ground or running downhill, the computer switches off four cylinders, turning the V-8 into a V-4. When you need more power, all cylinders come back on.

Around town, the Tahoe Hybrid's fuel economy is comparable to a four-cylinder Chevy Malibu (21 mpg vs. 22 mpg, respectively). While driving a 94-mile test run, I achieved 21.6 mpg in town and 24.1 mpg on the highway. Of course, I was driving to maximize fuel economy, but those are achievable numbers.

One note of caution: Beware of high voltage. Train your technicians before letting them work on hybrids. Even 42 V can cause injury, and 300 V can kill.

— Paul Abelson is a former director of the Technology and Maintenance Council of the American Trucking Association, a board member of Truck Writers of North America, and active in the Society of Automotive Engineers.