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Charlotte Transit Acquires Two GM Diesel-Hybrid Buses

The Charlotte (NC) Area Transit System (CATS) is adding two GM-Allison diesel-electric parallel-hybrid buses to its mass transit fleet.

The hybrid electric buses go into operation on Monday, 22 August. During the first week of use, customers will ride for free when a hybrid vehicle is used on their route.

To date, GM has delivered 364 hybrid buses to urban mass transit systems in 25 cities. Suggested improvements in fuel economy range from 20%–55% depending on the route and driving conditions, although some cities, such as Seattle, have had lower results. (Earlier post.)

The hybrid buses significantly lower emissions, including 90% fewer particulate, hydrocarbon and carbon monoxide emissions.

The hybrid powertrain technology in these buses has served as the starting point for GM’s co-development with DaimlerChrysler of a two-mode hybrid drive system that GM will launch in the Chevrolet Tahoe and GMC Yukon in late 2007.

In addition to the hybrid electric vehicles, CATS uses ultra low sulfur diesel (ULSD) fuel on 60 of its buses. The agency also is using diesel particulate filters on a select number of buses.


Joseph Willemssen

"although some cities, such as Seattle, have had lower results."

That's an understatement.

Expensive new hybrid diesel-electric buses that were portrayed by King County Metro as "green" heroes that would use up to 40 percent less fuel than existing buses have fallen far short of that promise.

In fact, at times, the New Flyer hybrid articulated buses have gotten worse mileage than the often-maligned 1989 dual-mode Breda buses they are replacing. Yet the hybrid buses cost $200,000 more each than a conventional articulated diesel bus.

Gilbert W. Arias / P-I
Metro's articulated hybrid buses were getting 3.75 miles a gallon in September.
The disappointing results are a far cry from the rosy predictions made by officials.

In May of this year, when Metro held a public event to herald the arrival of the first of the new hybrid buses, County Executive Ron Sims said they would save 750,000 gallons of fuel a year over the Bredas.


When he checked recently, Boon was told that Bredas are running at about 3.8 miles per gallon, while the conventional diesel older New Flyer articulated buses are running about four miles per gallon. The hybrids were getting 3.75 miles per gallon in September, but that has improved as the engines are getting broken in, Boon said. He expects further improvements with software tweaks.

"I've got hybrids that are getting four," he said recently. And Boon said he was surprised when he was told that Bredas were getting 3.8, because they've more typically been below 3.5.

Overall, the hybrids are getting about equivalent mileage to the older buses, Boon agreed.

It's not really a fair comparison, though, since as they point out later in the article, new Federal emissions rules forced them to swap out their Cummins engines for Caterpillar engines which had better emissions but weren't optimized for fuel economy.


Do the old Bredas have the same number of seats as the articulated GM hybrids?

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