New York ? New York City will have a fully hybrid fleet of yellow taxicabs by 2012, with new mileage standards kicking in as early as next year, Mayor Michael Bloomberg proposed Tuesday.

Beginning in October 2008, all new taxis in the fleet will be required to achieve a minimum of 25 miles per gallon. One year later, newly purchased cabs will be required to achieve a minimum of 30 miles per gallon.

Given the fuel efficiency of vehicles available on the market today, these new environmentally friendly standards would effectively limit the fleet to hybrid vehicles, city officials said.

“It will be the largest, cleanest fleet of taxis anywhere on the planet,” Bloomberg declared.

The announcement comes a month after Bloomberg unveiled an ambitious 127-point plan he described as the broadest scale attack on global warming undertaken by any city ever.

The Ford Crown Victoria, which accounts for roughly 90 percent of the city’s 13,000 yellow cabs, gets 14 miles per gallon. By increasing fuel efficiency to 30 miles per gallon, officials estimate the average taxi operator will save more than $10,000 per year.