Are on-demand rides a zero-sum game? Last week’s revelation that Uber reaps 12 times as much revenue as Lyft and provided seven times more car rides left the impression that its rivals had nothing left to do but eat its dust. FutureAdvisor’s study of credit-card receipts didn’t even consider smaller ride companies. A much narrower study of San Francisco riders from a UC Berkeley team, found that Uber commanded 61 % of rides; Lyft 30% and Sidecar 7%.

But don’t write off Sidecar. The San Francisco company said Monday that it had raised $15 million to expand its footprint nationwide and to fuel its “Shared Rides” carpooling option. Virgin co-founder Richard Branson joined existing investors Avalon Ventures and Union Square Ventures.

The British billionaire made clear that he doesn’t think the book is closed on the ride company wars.

“An entrepreneurial company like Sidecar can take on the big guys with innovation and big ideas, not just big bank accounts,” he said in a Q&A with Sidecar. “It has been reported this is a winner takes all market, but it’s not. These are early days and, like a lot of other commodity businesses, there is room for innovators on great customer experiences.”

Branson, who also invested in taxi-hailing app Hailo, added: “Technology has turned transportation on its head. It’s fundamentally changing the way we get around. It has changed the taxi industry and allowed them to automate.”

The new funding brings Sidecar’s total raised to $35 million. Lyft has raied hundreds of millions; Uber, over a billion.

All three companies last week received notices from California regulators that their car-pooling options violate a state ordinance, but that appears to be a way to prod them to ask legislators to update the law.