Mayor Michael Bloomberg promised relief last week to residents who are tired of seeing government cars parked illegally. The cars, sporting a mélange of real and fake parking permits, which city workers are only supposed to use on official business, regularly sprawl in bus stops and beside fire hydrants. No one knows how many permits there are -- legal or otherwise -- because so many agencies can issue them.

Bloomberg's plan calls for the city to count all the permits and requires each city agency to reduce its count by 20 percent. Currently, a range of agencies, from the Department of Education to the Office of Emergency Management, can issue their own permits at will. But starting March 1, the only agencies to issue the permits will be the New York Police Department and the Department of Transportation.

To better enforce permit-parking regulations, the N.Y.P.D. will create a special unit that will focus on preventing permit abuse. The plan will not affect state and federal agencies that issue placards.

Illegal permit parking is at its worst in Chinatown and near City Hall, so those areas will be the first to see a positive impact from the mayor's plan, said Wiley Norvell, communications director at Transportation Alternatives.

"We like what we see," Norvell said of Bloomberg's plan. "This promises to be more sweeping than everything we've seen before."

Norvell was most pleased by the N.Y.P.D.'s promise to crack down on permit abusers.

"It all comes down to enforcement," he said. "If the police start enforcing the law, we're going to see a huge change on our streets."

The Straphangers Campaign released a statement approving of the mayor's plan, anticipating that it will reduce traffic and promote public transportation. The campaign suggested that the city release the number of permits each agency is allowed to have.

A Transportation Alternatives study estimated that there are more than 150,000 permits -- the city puts the estimate closer to 70,000 -- but "Nobody knows how many are out there," Norvell said. "The fact that the city will finally take an inventory is a really big deal." The Transportation Alternatives study also found that 77 percent of permit holders abuse their privileges.