General Motors has made its interest in the ride-sharing market abundantly clear, and if its $500 million investment into Lyft, or its acquisition of Sidecar’s assets weren’t enough to convince you of that, then maybe the fact that it’s launched its own car-sharing service will be. Notice that I said car-sharing instead of ride-sharing, and that’s because the new service, known as Maven, allows users to share their unused vehicles with each other, rather than giving them rides. The service is currently limited to Ann Arbor, where users can drop off and pick up unused vehicles at 21 parking lots throughout the city, but Maven will expand to more cities in the United States later this year.