While diesel-electric hybrid
buses account for only about 10 percent of all U.S. transit agency buses, in three to five years, we should have a 50% chance of stepping on a diesel-electric hybrid bus, according to DaimlerChrysler. The CCO for the DCX Commercial Bus unit is quoted in a Reuters article
that the majority of Metropolitan transit agencies are increasingly considering alternatives when replacing aging diesel
buses. The diesel-electric hybrids provide a 33% or higher improvement in fuel economy
over traditional buses, at a cost premium of about 40%. A quick calculation
, assuming the bus does about 100,000 miles a year and diesel costs $2.85 a gallon, shows the hybrid premium will pay off in about 6 years of operation. From looking at some of the buses around where I live, I believe buses are kept in service quite a bit longer then that, so the decision seems to make economic sense. A hybrid-electric powertrain could also allow the diesel engine to go through less transient modes, which tend to cause the majority of the soot emissions. This looks like a win-win situation to me.