According to business weekly Wirtschaftswoche, Deutsche Bahn is working on an app that will integrate its existing Flinkster service with Daimler's Car2Go and BMW's DriveNow to book cars.
The principle behind the car-sharing scheme is to have cars available for rent more quickly and more widely.
Until now, most of the cars have been available in large cities, where customers can pick them up at short notice and return them, with automatic charges made to their accounts based on how many kilometres they have driven.
Wirtschaftswoche reported that under the new network, Deutsche Bahn would also work with Opel, Ford, Peugeot and Citroën dealers, and offer reservations and booking services for them.
Flinkster, with 2,500 cars and 190,000 customers, currently has 55 percent of the car-sharing market in Germany. Deutsche Bahn has said it wants to double its fleet of cars by 2014.
The rental agency Opel Rent reportedly would not comment directly on dealings with Deutsche Bahn, but did confirm negotiations with “one of the largest German car-sharing companies.”