The Google carpooling service, powered by navigation app Waze, could be a rival to services like UberPOOL, and comes on the heels of reports that Alphabet executive David Drummond resigned from Uber's board of directors over concerns about a conflict of interest.
Google's ride-sharing service began as a pilot program around the company's headquarters, and charged riders at most 54 cents a mile, according to the Journal. That's less than most rides from Uber, or competitor Lyft, the Journal said, although Google's app focuses specifically on shared rides, rather than on-demand taxi services.
Anyone with the Waze app in the San Francisco area could participate, the source told the Journal. The project builds on Waze's past ride-sharing ambitions, as well as Google's hopes for its self-driving technology, the Journal reported.
Google did not immediately respond to CNBC's request for comment.