Update: These trucks are being discontinued. A better design will be coming out, but there will be a gap when the hybrid version isn't available. It looks like GM still has some in their inventories, and used ones are available (check sites like Carmax).

M introduced their first hybrid vehicles in 2004, the Chevrolet Silverado and GMC Sierra hybrid pickups.

These really aren't hybrids in the strict sense. An electric motor doesn't help move the truck. The vehicle simply has the feature that shuts off the engine at a stoplight. Also, regenerative braking is used. Here's a good comparison chart from the Union of Concerned Scientists' hybridcenter.org site.

photo: altfuels.org

The trucks get about a 10 to 12 percent improved fuel economy over GM half-ton pickups. Having a belt alternator starter (BAS) system is a step in the right direction. It's a relatively simple and low cost system compared to the hybrid designs developed by Honda and Toyota. The emissions levels reported on the EPA's website aren't particularly good. The Silverado 4WD gets a greenhouse gas emissions rating of 10.6 tons and an air pollution score of 3 (out of a possible 10).  That compares to the Ford Escape Hybrid 4WD's 6.2 tons of greenhouse gases and an air pollution score of 7 (for the "50 state" model Escape available outside of California).

This truck represents an interesting variation of hybrid design. It has a built in 20-amp, 2400-watt generator.  The GM hybrid pickups feature four electrical power outlets that can be used while driving or when parked. The truck's generator can operate when the truck is parked without a key in the ignition and can be used to power anything from tools at a construction site to appliances at a campsite.

In the event of a power outage, the hybrid Chevrolet Silverado and GMC Sierra pickups can power tools or appliances for up to 32 hours non-stop. This design shuts the engine down before the tank is emptied, leaving enough gas to drive to a station for refueling. The power supply circuits are protected by a ground fault detection system to prevent overloads and short circuits.

The Hybrid versions start at about $30,000. 2WD and 4WD versions are available.

GM plans to add displacement on demand in 2007, which deactivates some cylinders under certain conditions. This should give a further increase in fuel economy.