On-demand car service Sidecar today announced a new $15.8 million funding round led by Avalon Ventures. Union Square Ventures and Virgin founder Richard Branson also participated in the round.

The new funding follows the launch of Sidecar’s “Shared Rides” carpooling service, which was announced shortly after Uber and Lyft teased similar services back in early August.

Sidecar tells us it has raised $35 million to date, following a 2013 $10 million round led by Union Square Ventures (announced in February 2014) and a 2012 $10 million round led by Lightspeed Venture Partners and Google Ventures.

According to a public filing with the SEC, Sidecar could raise $2.1 million more. We’ve reached out to Sidecar for more details on the matter and included the full SEC filing below: