The demand for hybrid vehicles in the U.S. is finally kicking in. The GM Allison Hybrid Bus is, yet again, another milestone for the diesel-electric hybrid technology.

Being one of the first large vehicle commercial hybrid parallel systems, the Allison Hybrid Bus features a diesel-electric powertrain which delivers ninety percent less nitrous oxide into the atmosphere while achieving fifty percent better acceleration than a bus equipped with a normal diesel power-train. It is a full-hybrid vehicle which means the electric motor will propel the bus at low speeds and only at higher speeds does the diesel engine kick in. This is why you will notice a large puff of black smoke coming from the rear end of the bus.

The Allison Hybrid Bus diesel engine is also used to recharge the battery pack along with the regenerative braking system. It delivers up to sixty percent better fuel economy than the conventional diesel system used in city buses.

At present, the Allison is carrying passengers in Seattle, Philadelphia, Minneapolis, Portland, Salt Lake City, Austin, Hartford, Houston and Orange County, California.

According to Tom Stephens, group vice president of GM Powertrain, "The parallel hybrid electric system is the most efficient hybrid architecture available in the world today. In addition to bringing the benefits of hybrid electric technology to commercial vehicles, our Allison Electric Drive System is helping establish hybrid technologies as effective, practical and commercially viable beyond mass transit applications."  GM is indeed in the right line by introducing hybrid technology to the most fuel consuming and polluting vehicles.