A hybrid electric bus is a form of bus that uses hybrid electric vehicle technology for propulsion, instead of the conventional diesel engine.
Current manufacturers of diesel-electric hybrid buses include New Flyer Industries, Gillig, Motor Coach Industries, Orion Bus Industries, and North American Bus Industries. In 2008, Nova Bus, which had previously marketed the RTS hybrid before that model was discontinued, will add a diesel-electric hybrid option for its LFS series as well.
In the United Kingdom, Wrightbus has introduced a development of the London 'Double-Decker', a new interpretation of the traditional red buses that are a feature of the extreme traffic density in London. These buses use a small diesel engine with electric storage through a lithium ion battery pack. The use of a 1.9 litre diesel instead of the typical 7.0 litre engine in a traditional bus demonstrates the possible advantages of serial hybrids in extremely traffic-dense environments. Based on a London test cycle, a reduction in CO2; emissions of 31% and fuel savings in the range of 40% have been demonstrated, compared with a modern 'Euro-4' compliant bus.
Also in 2005 GE introduced its hybrid electric shifters on the market. Toyota claims to have started with the Coaster Hybrid Bus in 1997 on the Japanese market. In May 2003 GM started to tour with hybrid electric buses developed together with Allison. Several hundreds of those buses have entered into daily operation in the US. The Blue Ribbon City Hybrid bus was presented by Hino, a Toyota affiliate, in January 2005. Mitsubishi Motors have developed a diesel engine hybrid bus using lithium batteries in 2002, and this model has since seen limited service in several Japanese cities.
