WASHINGTON,DC. JAN..4, 2013. When D.C. resident Nathan Graeff isn’t using his car, he rents it out to others nearby for short periods through start-up RelayRides.1/4/13. (Jeffrey MacMillan/JEFFREY MACMILLAN FOR CAPITAL BUSINESS)

District resident Nathan Graeff, a Metro contractor, takes the subway to work near Foggy Bottom from Columbia Heights each weekday.

For weeks on end, his 2006 Chevrolet Cobalt used to stand parked outside his residence. Graeff kept the car for occasional visits to his family in Pennsylvania and for trips to Ikea and the grocery store, but for the most part, it was untouched.

“I’d rather have someone else utilize it,” he said.

In March, Graeff decided to lend his car to other D.C. residents who might need his car while he’s not using it— during daytime hours on weekdays and before 1 p.m. on weekends. He had searched for car-sharing platforms online, but only found one, called RelayRides, operating in D.C.

San Francisco-based start-up RelayRides is a peer-to-peer car-sharing service allowing car owners like Graeff to rent out their cars to people nearby needing a car for a few hours or a day.

RelayRides is one of a handful of businesses using the peer-to-peer model — others, which don’t yet have a D.C. presence include Getaround, mostly functioning on the West Coast, and Buzzcar, only available in Europe.

The services suggest that car-sharing models are evolving, even as an early pioneer such as Zipcar gets snapped up by rental giant Avis for almost $500 million.

Graeff’s car has been rented eight times so far, netting him an extra $250. He adjusts his asking price depending on his perception of demand — right now, it’s $8 an hour, $50 a day, or $320 a week. His renters have mostly needed the car for a couple of hours for errands, and Graeff usually meets renters to hand off the car and keys.

RelayRides takes 40 percent of the owner’s rental fee, which pays for administrative costs and an insurance policy (each car is covered for up to $1 million), according to the company. It also screens potential renters by running a license and credit check.

Growing fast

While the company won’t disclose numbers of owners or renters, RelayRides chief executive Andre Haddad noted that its user base is growing fast, expanding from two cities at the beginning of the year to 1,200 in 49 states. (The service is available in all 50 states, but so far no users have signed up in North Dakota, according to the company.)

D.C. is in the top six markets for RelayRides across the country, he said.

Systems like RelayRides’ fit into a larger “sharing economy,” Haddad said. Other examples of sharing marketplaces include Airbnb, whose platform allows individuals to rent their property as short-term lodging to guests, or TaskRabbit, which lets people earn money by completing errands requested by other users, Haddad noted.

This kind of model may not attract the entire population, however. In the case of RelayRides, renters and owners are most commonly part of the “millennial generation” with average ages of 33 and 34, respectively.

Haddad attributes this popularity to “an attitudinal and behavioral change we’re seeing with younger people” who are generally “less enthusiastic about car ownership, and more interested in socializing virtually.”

The recent growth of the sharing economy could also be driven by economic stagnation. “More and more people are thinking about asset utilization — how they can make money from assets they own,” Haddad said.