Yet as Uber tries to muscle deeper into Germany after a three-year hiatus, it faces more competition. A service owned by BMW, DriveNow, lets people rent a car with an app for short trips around cities such as Berlin. Moia, a subsidiary of Volkswagen, is testing a ride-sharing bus service in Hamburg. MyTaxi, a taxi-dispatch app owned by Daimler, is also widely used. And there are fast-growing rivals such as Taxify, which provides rides in European cities.

“It’s very hard for them to compete on so many fronts at once,” Markus Villig, Taxify’s chief executive, said of Uber. Unless Uber can win major changes to German regulations, he said, “they are in a very tight spot.”

Uber said it had selected Düsseldorf as its re-entry point for expanding in Germany after seeing that customers there had logged into its app more than 150,000 times since January, even though no cars were on the road. Düsseldorf, about 350 miles west of Berlin, is a business hub and home to popular festivals that draw travelers. One boisterous area of town, called “The Longest Bar,” has more than 260 bars and dance clubs.

Uber knew it could not open in Düsseldorf as it had in 2014, when it first arrived. That year, Uber didn’t bother warning local officials it was coming. One morning, the app simply went live, and anybody was free to transform his or her car into a taxi without a license.