ZipCar is probably the most well-recognized car-sharing service available in the United States today. However, a new car-sharing company is bringing its unique concept to market, pairing car owners with individuals who need a short-term rental car. RelayRides is hoping to capitalize on underused vehicles in the U.S. and turn these parked cars into a revenue stream for the car owner and RelayRides.

This new car-sharing opportunity isn’t just a financial win for car owners, renters and RelayRides; it also has positive environmental benefits. According to RelayRides, a shared car replaces 14-18 cars on the road, those who car share are on the road as much as 70 percent less than those who don’t, and of course when there are fewer cars on the road, there is less pollution.

In order to participate in the program as a renter, you need to be at least 21 years of age. The company will make exceptions for adults as young as 18 as long as their driving record is impeccable, they’ve been a licensed driver for a minimum of two years, and they carry their own auto insurance policy. One benefit of using RelayRides over a traditional car rental company is that there are no age-related premiums.

RelayRides has developed a comprehensive pricing plan with both hourly and daily rates available. Prices start at $6 per hour for an economy vehicle that is model year 2003 or older. Prices top out at $12 per hour for a specialty vehicle that is model year 2007 or newer.

In addition to the base prices, there is a separate fee for excess miles. RelayRides has determined that anything over 20 miles per reservation hour or 160 miles per day is excess. There is no fixed cap on rental length. The beauty of this program is that a car is available for as long as the participating owner designates — which can be up to weeks at a time.

While the program has some obvious benefits for renters, RelayRides helps assuage potential owners' concerns with a detailed set of frequently asked questions. The first question addressed is the potential profit that owners can receive by participating in the program. Owners of a brand new 2010 luxury car that rent out a vehicle for 20 hours per week could earn about $8,000 in a year. Income potential does vary based on the year of the vehicle, the type of vehicle and the condition of the car.

Another big question that potential owners will have is what happens if someone has an accident while driving their vehicle. RelayRides maintains an auto insurance policy beyond that carried by the owner. This policy will pay for repairs or replacement costs as well as provide the owner a rental car during the repair period.

RelayRides is just getting started and will soon be launching their service in Baltimore, Md. Consumers who are interested in the program but don’t live in Baltimore are encouraged to sign up on the RelayRides site. As new cities are added, e-mail notifications will be sent.

Photo: RelayRides