From an article by Steve Schultze in the Milwaukee Journal Sentinel:

Hybrid diesel-electric buses run cleaner and quieter and get better mileage than their conventional diesel engine counterparts, advocates say.

Dozens of cities around the United States use hybrids, including Madison, Chicago and New York. But don’t expect to see them anytime soon in Milwaukee.

Higher hybrid costs have put them out of reach for the Milwaukee County Transit System, at least for now. The local bus system is seeking $16.4 million in federal stimulus aid, which it plans to use to replace 41 aging diesel-powered buses with new diesel buses, transit system managing director Anita Gulotta-Connelly told county supervisors this week.

The big reason is cost. Hybrid models each cost about $500,000, or up to $200,000 more than conventional diesel buses, according to an analysis by the Union of Concerned Scientists, a national environmental policy advocacy group. The hybrids also cost an extra $30,000 to $60,000 in expected costs of replacing their battery packs, according to a report from the transit system.

Cheaper fuel costs for the hybrids – they get about 30% better mileage – would save up to $85,000 over the 12-year life of a bus if diesel fuel averaged $3.50 a gallon, the transit system report says. That still makes traditional diesel buses more affordable.