Given the stop and go nature of traffic in New York City, the promise of increased fuel efficiency from hybrids is too good to pass up. Mayor Michael Bloomberg announced yesterday on the "Today" show that every yellow cab will be a hybrid by the year 2012.

There are roughly 13,000 taxis roaming city streets (90 percent of which are gas guzzling Ford Crown Victorias). According to Bloomberg, 20 percent of the existing yellow cab fleet will be replaced each year until all are running on hybrid power. Currently, there are only 375 hybrid taxis on the road in NYC.

"There's an awful lot of taxicabs on the streets of New York City obviously, so it makes a real big difference," said Bloomberg. "These cars just sit there in traffic sometimes, belching fumes; this does a lot less. It's a lot better for all of us."

There are currently eight vehicles on the city's "approved" list when it comes to hybrid vehicles to be used as yellow cabs: the Ford Escape Hybrid; the Honda Accord Hybrid and Civic Hybrid; the Lexus RX400h; the Saturn Vue Green Line; and the Toyota Highlander Hybrid, Camry Hybrid and Prius. As more manufacturers roll out fuel efficient hybrids, the number of possible candidates is sure to increase. Vehicles like the Saturn Aura Green Line and rumored Ford Fusion hybrid are likely to join the list.

Ford Crown Victorias are rated at 15 MPG in city driving. A Ford Escape Hybrid, however, is rated at 31 MPG in the city according to the new 2008 EPA estimates. Hybrids like the Camry and Prius are even more fuel efficient at 33 MPG and 48 MPG respectively.

The Ford Escape Hybrid has already seen extensive use in San Francisco. Taxi operators reported on their vehicles once the 100,000 mile mark was surpassed. According to the operators, fuel savings compared to the Crown Victoria were between $20 to $31 per shift. Air conditioning costs were also roughly half that of Crown Victorias. Another plus was that the brakes lasted twice as long due to the hybrid system's regenerative braking feature taking a load off the traditional braking system. Most importantly, there were no complaints of poor rear legroom from passengers.

Yahoo Inc. has already committed to donate 10 Ford Escape Hybrid taxis according to Bloomberg.

When all is said and done, the switch to a completely hybrid yellow cab fleet will save each taxi operator over $10,000 USD per year in fuel costs while also cutting total carbon emissions by 200,000 tons per year.