San Francisco may have the biggest green fleet in America now that all 1,500 diesel vehicles—including ambulances, fire engines, buses and street sweepers—run on B20, a combination of soy-based and diesel fuels. The transformation is part of the city's plan to reduce toxic emissions to 20% below 1990 levels in the next four years, the New York Times reports.
The announcement comes as Congress haggles over the details of an energy bill to encourage automakers to make biofuel-powered cars. But San Francisco Mayor Gavin Newsom is ahead of the game: His next plan for reducing the city's carbon emissions is "SFGreasecycle," a project that would collect restaurants' used cooking oil to make biofuel. (Read more San Francisco stories.)