General Motors and RelayRides - a peer-to-peer car-sharing company - are teaming up to create a program that allows GM vehicle owners to rent out their idle cars through the RelayRides marketplace.

The program, set to launch in early 2012, is GM's first large-scale involvement in car sharing. It is aimed at making it easier for those without a vehicle to access temporary and affordable transportation in a Chevrolet, Buick, GMC or Cadillac.

Through RelayRides, GM vehicle owners can choose to rent out their idle vehicles while remaining in control of the rates and availability of the car. RelayRides additionally provides an online marketplace and a $1 million insurance policy to make the transaction safe and convenient.

RelayRides will leverage OnStar to allow RelayRides borrowers to unlock GM cars with their mobile phones. The mobile phone application will also allow customers to check for available vehicles, make a reservation online as well as check future reservations, and locate their reserved vehicle via GPS.

For vehicles that are not OnStar enabled, RelayRides must install a small device in the car to provide convenient access to borrowers.

"We're using technology to make both our older and newest models carshare ready and available for those owners who choose to participate in car sharing," said Stephen Girsky, GM vice chairman. "Our goal is to find ways to broaden our customer reach, reduce traffic congestion in America's largest cities, and address urban mobility concerns."

The program will be promoted through various events and demonstrations in California to showcase GM's OnStar and RelayRides technology. It will also feature Chevrolet vehicles, including the Volt extended-range electric vehicle.