NEW YORK - The city's yellow taxi fleet will go entirely hybrid within five years, announced New York City Mayor Michael Bloomberg.

Nearly 400 fuel-efficient hybrids have been tested in the city’s taxi fleet over the past 18 months, with models including the Ford Escape, Toyota Prius, Toyota Highlander Hybrid, and the Lexus RX 400h. Under Bloomberg's plan, that number will increase to 1,000 by October 2008, then will grow by about 20 percent each year until 2012, when every yellow cab — currently numbering 13,000 — will be a hybrid.

The standard yellow cab vehicle, the Ford Crown Victoria, gets 14 miles per gallon. In contrast, the Ford Escape taxis get 36 miles per gallon.

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. Bloomberg made the announcement on NBC's "Today" show.

Hybrid vehicles are typically more expensive, but the city said the increase in fuel efficiency will save taxi operators more than $10,000 per year. Yahoo Inc. said it would donate 10 hybrid Ford Escapes for the city's effort.

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.