GM estimates the hybrid buses will save 2.4 million gallons of fuel a year, enough to fill 300 tanker trucks.
GM announced the bus orders last week at the Washington Auto Show. About 1,000 of the GM-Allison hybrid buses are now in service.
The Washington Metropolitan Area Transit Authority ordered 952 hybrid buses, GM says. The Southeastern Pennsylvania Transportation Authority ordered 480, and the Minneapolis/St. Paul transit system plans to buy as many as 300 hybrid buses.
GM launched its hybrid technology for transit buses in 2003. The automaker says the buses are in service in 81 cities in the United States, Canada and Europe.
