With a plan already under way to make all of New York City's yellow cabs green by 2012, Mayor Michael Bloomberg recently proposed new fuel-efficient rules for the thousands of black cars used by car services, the Associated Press reports.

Under the proposal, the 10,000 or so black cars operating citywide would be required to meet a fuel efficiency standard of 25 miles per gallon in 2009 and 30 miles per gallon in 2010. Black cars now average 12 to 15 miles per gallon.

Black cars, which are often used by the business community, are usually summoned to a specific location, not hailed on the street, which is one of the reasons Bloomberg said it is important that they go green.

By setting the fuel efficiency rule for town cars, which will go for a vote before the Taxi and Limousine Commission in April, the Bloomberg administration estimates drivers will save thousands of dollars per year in gasoline expenses.

To help defray the sizable cost of purchasing hybrid vehicles, the Bloomberg administration recruited financial institutions to chip in on a financing program.

According to the AP, the town cars are estimated to contribute 272,000 tons of carbon emissions each year, or 2 percent of the city's total load of emissions from transportation sources.