In an unusual pairing of business and environmental interests, five neighborhood business groups are asking the Bloomberg administration to do more to relieve congestion on city streets, citing a new study of private car traffic in Manhattan.

The business groups, representing property owners in Manhattan, Brooklyn and Queens, signed a letter sent last week to Deputy Mayor Daniel L. Doctoroff that criticizes "current piecemeal efforts to relieve traffic and promote alternatives to driving."

The City Hall letter was accompanied by an advance copy of a study, to be released today, that was commissioned by an advocacy group, Transportation Alternatives. Relying largely on government data, it concludes that private cars far outnumber buses, trucks and commercial vehicles, many people entering Manhattan by car are simply passing through, and 90 percent of commuters in private cars could be using public transportation.

"This makes it clear that we don't have to accept the old argument that restricting automobile use will hurt the economy," said Paul Steely White, the executive director of Transportation Alternatives, a 32-year-old advocacy group supported by member contributions and foundation grants.

The study, conducted by Bruce Schaller, a transportation consultant who has extensively worked for the Metropolitan Transportation Authority and the city's Taxi and Limousine Commission, offers no broad solutions. But it proposes a series of steps long advocated by transportation planners: dedicating more space on the streets for buses and bicycles and freeing more sidewalk space for pedestrians.

"We wanted to jump in with both feet and say we agree," said Barbara Adler, the executive director of the Columbus Avenue Business Improvement District on the Upper West Side of Manhattan. Also signing the City Hall letter were a nearby Manhattan group, the Columbus-Amsterdam Avenue Business Improvement District; two groups in Brooklyn, the Myrtle Avenue Brooklyn Partnership and the North Flatbush Avenue Business Improvement District; and the Sutphin Boulevard Business Improvement District in Queens. "We are not saying 'put an end to cars,' " said Mirvlyn Brice, the executive director of the North Flatbush Avenue group, which represents a congested business strip between Atlantic Avenue and Grand Army Plaza. "We are focusing on how we can make things more pedestrian friendly."

Jennifer Falk, a spokeswoman for Mr. Doctoroff, said he was reviewing the letter and the study, but declined to comment further.

Mr. Schaller's analysis, entitled "Necessity or Choice: Why People Drive to Manhattan," raises questions about how passenger cars affect the city's economy. It found that most people who drive into Manhattan below 60th Street do so because of the comfort and convenience of their cars, ignoring easily available public transportation.

Sixty percent of the vehicles on those streets are passenger cars, and congestion has surged since 2001, the study found.

The study found that a large share of people driving into Manhattan are bound for somewhere else and therefore contribute little to the city's economy beyond bridge or tunnel tolls. It said 61 percent of those crossing East River bridges were making through trips and that more than 30 percent of those using Hudson River tunnels were bound for destinations outside Manhattan's main business district.

The analysis also underscored some of the political tensions that surround restrictions on car use and have emerged in the past when officials have suggested measures like congestion pricing — imposing a fee to drive into the business district when traffic is heaviest — as a method to discourage people from driving at peak times.

It found that more people who live in other parts of the city commute by private cars into the main Manhattan business district than those who live in the suburbs. The largest number of city drivers are in Brooklyn and Queens, the study found, making them unlikely to support congestion pricing by way of East River bridges.

Support for restrictions on private cars is not fully shared among business people. The business groups publicly supporting such restrictions represent less than 10 percent of the city's business improvement districts, and none of them are in the main business district.

But executives said there had been a broad shift in attitudes from the days when business leaders almost universally sought greater access for their customers and employees who wanted to drive into Manhattan from the suburbs.

"There has been a gradual shift over 30 years," said Daniel A. Biederman, the executive director of the Bryant Park Restoration Corporation. Although many business owners might still oppose stiffer restrictions on private car use, "it would be closer to 50-50," he said, "and there wouldn't be strident opposition."

Tim Tompkins, the president of the Times Square Alliance, a group that has struggled for years with the problems of gridlocked vehicular and pedestrian traffic, responded cautiously to the Transportation Alternatives report.

"You can think of the transportation system as the arteries of the city economy, and there is no doubt that the arteries are clogged," he said. "But you have to proceed carefully and make sure the oxygen gets through."