The National Renewable Energy Laboratory has been tracking a fleet of hybrid buses operating in Seattle, Washington for the past year and has just issued their final report. The fleet of ten New Flyer buses are equipped with a GM-Allison two-mode hybrid drive-train, similar to the one that will be used late next year on GMT900 SUVs as well as Chrysler and BMW vehicles. The study compared the hybrid buses against standard diesel buses running similar duty cycles. The hybrid buses achieved 27 percent better fuel economy, while the diesels also had 4.5 perent higher maintenance costs. When the fuel and maintenance costs are combined, the hybrids had an operating cost of $1.06 per mile while the diesels were at $1.25 per mile. Emissions testing of a hybrid and diesel bus also showed an advantage for the hybrid.
[Source: National Renewable Energy Laboratory via GreenCarCongress