General Motors and RelayRides, a car-sharing service based in San Francisco, announced yesterday a joint venture that will eventually allow owners to temporarily loan out their OnStar-equipped cars to strangers—for cash.

RelayRides is similar to community bike-sharing programs. Participants list on the company's website the availability and rental rates for their personal cars, which are equipped with special RelayRides gear. The company manages the transactions and provides a $1 million insurance policy to protect both the renter and car owner.

However, the two-year agreement with GM will allows the car-sharing network to expand its reach to nearly any consumer with an OnStar-equipped car. Those owners who choose to opt-in to the RelayRides program will no longer need special equipment installed. A simple call to GM's OnStar service center will allow renters to control borrowed cars' doors and engines without the owners' keys.

The specifics of the set-up are still being ironed out. But GM and RelayRides expects to roll out the option to OnStar members in California by next year.

GM Enters Carsharing Business; Teams Up with RelayRides [General Motors' press release]
GM Partners With Personal Car-Sharing Business RelayRides [ABCNews]
GM teams with car-sharing company RelayRides [CNN Money]
GM dives into the car-sharing business [USA Today]