Tuesday, February 07, 2006

GMC Sierra Puts Hybrid in Big Pickups


Before you get all excited and rush out to your local GMC dealer to plunk a big down-payment on the salesman’s desk, understand that there are hybrids and then there are hybrids.

A full hybrid can use either its electric motor or gasoline engine to move the vehicle. The best example of this stage of hybrid development is the Toyota Prius, which move at up to 30 mph using only its electric motor. This gets the maximum fuel and environmental benefits, such as they are.

Then there are what we might call the semi-hybrids like the hybrid editions of the Honda Insight, Honda Accord and Honda Civic. The electric motor is more of a supplemental performance booster to the gasoline engine in this approach, so the vehicle cannot move solely on the current.

Now we come to the Hybrid Lite class to which the GMC Sierra Hybrid and its Chevrolet Silverado brother belong. In this application, the 14 Kilowatt starter/generator replaces the alternator and starter motor.

The starter/generator is used to power accessories while the vehicle is stopped and the gas engine is turned off. Electric power is also stored for supplemental use and can be used to power external tools (though the gas engine has to be on for that use).

Hybrid purists may well dismiss the Sierra and Silverado hybrids as little more than public relations stunts by a GM desperate to catch up with other automakers that have pushed the technology further and faster. For its part, GMC claims the Hybrid provides up to 10 percent improvements in fuel economy, compared to the gas-only Sierra.

However you come down on that issue, I spent a recent week in a Sierra Hybrid and concluded that although small there are definitely concrete benefits to the system. The system is also virtually transparent, so it is hardly even noticeable.

Basically, the only time you notice anything different about the way the Sierra Hybrid operates is when you come to a full stop. Listen carefully and you will notice the 5.3 liter Vortex V-8 shuts down. The radio and all other accessories continue to work, however.

Push the gas pedal and the V-8 instantly refires and off you go. There is hardly any driveline clunk or shudder with the restart because the generator becomes the starter and is much stronger than a conventional starter.

Net result is that you’ve saved a bit of gasoline by switching the V-8 off and you’ve avoided a slight amount of emissions at idle. It may not be much but every little bit helps, right?

The hybrid option adds about $2,500 to the Sierra price and is only available on the two and four-wheel drive extended cab versions. For a four-wheel-drive version with Onstar and other popular options expect to see a sticker bottom line of around $37,735.

Is it worth it? Yes, if you want to encourage the hybrid movement in the marketplace. No, if you expect to see vast gains in fuel economy or emissions reductions. But like we said, every little bit helps, right?