The 10,000 black town cars used to shuttle corporate clients around New York City would be required to meet new fuel efficiency standards next year under a plan proposed by Mayor Bloomberg.

The cars would be required to meet a standard of 25 miles a gallon in 2009 and 30 miles a gallon in 2010, up from the 12 to 15 miles a gallon they average now. Drivers of yellow taxis also have been told they need to replace their vehicles with fuel-efficient hybrid cars by 2012.

About one-fifth of the city’s for-hire vehicles are black town cars, which are regulated by the city’s Taxi and Limousine Commission. Banks and law firms commonly hire the cars, which create 2% of the city’s transportation-related emissions.

Drivers would have to pay for the hybrid vehicles, which cost more than regular cars, but Mr. Bloomberg argued yesterday that the fuel-efficient vehicles would save about $5,000 a year in fuel costs.

“The savings when you drive a more fuel-efficient car really are significant for the driver, but from the rest of our point of views, it is infinitely better for the world that we live in,” Mr. Bloomberg said yesterday.

To reduce the cost of purchasing hybrid cars, city officials are pressing Albany lawmakers to pass a law waiving the city sales tax on fuel-efficient vehicles.

City officials also are working with a business organization, the Partnership for New York City, and financial institutions to provide financing for the new cars, and Lehman Brothers is teaming up with the largest black car supplier in New York, Executive Transportation Group, to give drivers low-interest loans to buy the new vehicles.

The Taxi and Limousine Commission is expected to vote on the proposal in April.