While major automakers have been pulling out of short-term rental programs, new players are nonetheless pushing into the space.
Among the companies still placing bets on this part of the mobility revolution are PSA Group and most recently, Penske Automotive Group.
But experts say it is a difficult landscape for any company to navigate — especially without a stable business structure.
"There's a lot of operational challenges with running this kind of business. So far, no one has come up with a viable operational model that makes commercial sense," said Sam Abuelsamid, principal analyst at Navigant Research. "For a lot of use cases, it's less convenient than just opening up the Uber or Lyft app and requesting a ride."
General Motors' Maven announced its venture would exit eight cities in May.
BMW and Daimler have recently melded their DriveNow and Car2Go into a joint venture called Share Now, which combined, they say, comprises the biggest free-floating short-term rental fleet in the world.
However, Share Now announced plans last month to scale back on its operations and pull its vehicles from five major North American cities by the end of 2019.
Penske Corp. launched its short-term rental pilot in Washington, D.C., and Arlington, Va., just last week. Penske Dash is a joint venture between Penske Corp. and Penske Transportation Solutions.
"When you think about '19 and beyond, as we see technology and we see ride-sharing and subscriptions, we think this could be a potential business for us," Penske Automotive Group CEO Roger Penske told Automotive News in January.
The leader of Penske Dash local operations, Paul DeLong, previously was CEO of the scaled-back Car2Go North America.
Michael Montri, COO of Penske Dash, told Automotive News in a statement that mobility as a service is part of a broader change in private car ownership.
"As the automobile industry undergoes rapid change, alternative transportation models are becoming more commonplace, particularly in densely populated urban areas," Montri said. "Our entry into any market will be methodical as we grow in partnership with local communities, pursuing customer satisfaction and repeat business as primary metrics rather than number of users or vehicles."