NEW YORK, NY May 22, 2007 —The city's fleet of yellow cabs is going hybrid. Mayor Bloomberg is set to announce today that all vehicles for hire will have to meet new emissions and mileage standards by next year.

And the fleet will go entirely hybrid within 5 years. Out of the 13,000 taxis currently rolling on city streets, just 375 of them are fuel-efficient hybrid vehicles. That number will increase to 1,000 by October 2008. And it'll grow by about 20% each year until 2012, when every yellow cab will be a hybrid. Hybrid vehicles, which run on a combination of gasoline and electricity, emit less exhaust and get better gas mileage.