Mayor Muriel E. Bowser is siding with ride-hailing companies over a D.C. Council recommendation to raise a revenue tax on Uber and Lyft to 6 percent, even for lower-cost options such as UberPool.

Bowser (D), who had pitched a 4.75 percent ride-hail tax to provide a portion of the District’s $178 million in dedicated funding for Metro, supports a tiered system pushed by advocates that would tax private rides such as UberX at 5.35 percent but keep the tax on pooled rides at 1 percent.

However, council recommendations released last week would raise the tax on all ride-share trips to 6 percent and would not exempt shared rides from the increase.

Bowser criticized that recommendation in a letter Monday.

By “raising the per ride tax for ridesharing companies to six percent across the board, the Council disincentivizes the use of pooled rides and unfairly disadvantages lower-income riders who rely on pooled service,” she wrote. “We support the progressive proposal to incentivize pooled rides that was put forth by a number of community groups and a coalition of ridesharing companies and approved by the Committee on Finance and Revenue.”

DC Sustainable Transportation, a coalition of business groups and smart-growth advocates, lauded the benefits of a tiered system last month in a letter to D.C. Council Chairman Phil Mendelson (D-At Large) and council members Mary M. Cheh (D-Ward 3) and Jack Evans (D-Ward 2). Evans also is Metro Board chairman.

Compared to single passenger private rides or people driving their own cars alone, pooled options help reduce traffic and pollution. In addition, they are the most affordable ride-hailing option. By taxing only single passenger options, you would help keep pooled rides affordable for low- and middle-income DC residents who may not be able to always pay for more expensive private rides.

The organization argued that the tiered system would position the District for a not-too-distant future. Ride-hailing companies signed on to the letter.

“Finally, it would be an initial step towards helping the District prepare for autonomous vehicles, which experts agree will have to be deployed on a shared basis in our cities if we are to realize their full benefits,” the letter said.

But the council argues that its tax increase is fair, citing research that shows that the popular ride-hailing services can have major downsides for cities. Uber and Lyft “contribute to traffic congestion, add wear and tear to the District’s roads, and there is evidence that they draw people away from public transit,” the council wrote.

Uber says it is not a public transit competitor — and in what it called a gesture of goodwill, the company stepped up this week to provide late-night service for Monday night’s Washington Capitals Game 6 at Capital One Arena in a deal organized with Bowser’s office. (Uber insists the timing of its deal with Metro, coinciding with Bowser’s backing of the company against the council provisions, is not connected. The company had tried to sponsor late-night service during last fall’s Washington Nationals playoff run but was turned down by city officials.)

Research has shown that 15 to 30 percent of trips taken using ride-hailing services would have otherwise been taken on public transit. And Metro is studying the effect that services such as Uber and Lyft are having on its declining ridership.

Meanwhile, council legislation unveiled last week would make it easier for city and transit officials to gain insights on Uber and Lyft’s effect on the local transportation network.  The proposal, which is tied to the budget, would mandate that ride-hailing companies submit extensive data to the D.C. departments of transportation and for-hire vehicles, including the number of drivers they have, how many vehicle miles are driven using their services and a meticulous log of each trip, including pickup and destination locations, among other details.

While Lyft previously expressed opposition to that proposal, Uber issued its own statement Tuesday outlining its concerns.

“The District has been a leader in the field of collaborative data-sharing, but we’re concerned that the current proposal risks exposing riders’ sensitive data, such as visits to medical clinics, immigration lawyers, and houses of worship, to public view,” Uber spokesman Colin Tooze said in a statement. “We’re working with the Council to find a solution that will allow District leaders to rely on accurate data to help make policy decisions without risking people’s privacy.”

Uber says it is not opposed to sharing data but wants to work with city officials to hash out a data-sharing agreement rather than be subjected to strenuous and potentially data-compromising regulations. It pointed to SharedStreets, a data-sharing collaboration between the National Association of City Transportation Officials and the Open Transport Partnership, as a possible avenue for enhanced transparency. (Through SharedStreets, Uber already shares limited data on curb use with DDOT.)

This post has been updated.