The rule change, expected since last spring and adopted Tuesday, will lead to a dramatic overhaul in the composition of New York's storied taxi fleet.
Right now, a majority of the city's 13,000 cabs are Ford Crown Victorias. But the Crown Vic's big V8 engine currently gets around 14 mpg, well short of the standard set by the Taxi and Limousine Commission.
The new rule will mean that taxi fleet owners, who must replace their cabs every three to five years, will probably be forced to buy fuel-efficient hybrids, which run partly on electricity.
Today there are fewer than 630 hybrid cabs in operation in the city, but the number has been growing steadily. Mayor Michael Bloomberg wants all city taxis to be hybrids by 2012.
TLC Chairman Matthew Daus said the fuel efficiency vote was "one big step for the TLC, but it was also a giant leap for the environment."
"This regulation, the first of its kind anywhere, lays the groundwork for the cleanest, greenest large city taxicab fleet in the world," he said in a statement.
Ford spokesman Jim Cain said he couldn't comment on what the rule change would mean for the future of the Crown Victoria in New York, but he said the company has been working on a number of fuel efficiency initiatives.
"We have very loyal customers in the taxi industry, and we are committed to that business," he said.
According to Cain, Ford sells about 3,000 Crown Victorias each year for use as New York taxis.