An online car rental marketplace known as RelayRides has taken root in West Marin, where a smattering of members are hoping to grow its presence. The group, on a mission to “revolutionize personal mobility,” was founded in 2010 by a Boston resident named Shelby Clark who conceived the idea on a bicycle ride through a blizzard on his way to pick up a rental car “while thousands of other cars sat idle” around him: “Eureka!” he declares on the website. “Why couldn’t those cars, some clearly parked for days, be available to rent?” RelayRides is headquartered in San Francisco and offers services in cities across the country—except New York, where the group suspended them after learning they conflicted with insurance laws. In West Marin, a shy two or three residents have signed up. But doing so is easy: go to relayrides.com; choose what kind of car you want and when you want it; enter your driver’s license and credit card numbers; get directions to your car, use it, return it; replace the gas you used; and leave feedback on the site. It’s just as easy to rent your own car; you determine the price, and insurance is included. It doesn’t cost anything to sign up, and the benefits are various: David Briggs, an Inverness resident and an employee of this newspaper, said he listed his car—“a pretty slick stock Camry Station Wagon, V6, with plenty of space inside and on top”—just to make some extra money. But, he said, “the only person that’s contacted me so far asked how close I was to Kona.” Another Inverness resident, Nina Pick, owns the only other RelayRide car in West Marin. She first used the service while living in Berkeley, and now rents her Honda Civic out for $6 an hour, $30 a day or $150 for a week. “What’s also cool is the community building aspect,” she said. “Ideally it would be great to have a strong enough car-sharing community that someone could live here without a car. The infrastructure is already set up, and we just tap into it.”