Oh, you mean the Rule of Thumb?
Shifting the taxi fleet to hybrids is part of Bloomberg's wider sustainability plan for the city, which includes a goal of a 30 percent reduction in carbon emissions by 2030.In addition to making the yellow cab brigade entirely green within five years, the city will require all new vehicles entering the fleet after October 2008 to achieve a minimum of 25 miles per gallon. A year later, all new vehicles must get 30 miles per gallon and be hybrid.
The two most common things in the Universe are hydrogen and stupidity. -- Harlan Ellison