After an uproar last year between Mayor Bill de Blasio and the ride-hailing app Uber over the company’s growth in New York City, the two sides reached something of a truce on Friday with the release of a very short — and very expensive — traffic report from the city.

The long-awaited report concluded that the mayor’s contention that Uber vehicles and other ride-hailing services had worsened traffic in Manhattan was unfounded.

The 12-page report was based on a $2 million study conducted after the clash last year over Mr. de Blasio’s plan to impose a cap on the number of Uber vehicles operating on city streets. The report recommended against enacting such a limit.

Uber and its rival Lyft both praised the mayor and the report, but the brevity of the document and the absence of supporting data surprised some experts, who said they had expected a more thorough examination.