Would you rent out your GM vehicle to strangers if OnStar could keep track of it for you?

Subscribers to GM's OnStar connected car service can now rent out their cars to others using the RelayRides service. GM's investment arm put money into RelayRides when it started up and now the partnership has expanded. GM has allowed the peer-to-peer car sharing network access to its API (application protocol interface) so that it can tie its mobile phone apps and website into the OnStar service, allowing GM customers to use RelayRides to rent their cars to others.

The OnStar integration means that the cars are continually tracked and can be located anytime by the owners, allaying some concerns over theft. The service also means that renters who've properly rented the car can gain access to it through OnStar.

The partnership was originally announced last October, but the service didn't go live until today. RelayRides is the first third party company to gain access to GM's OnStar API, but GM says they'll be opening it to other developers later this summer. GM hopes that adding new services like this will raise the retention rate for buyers who purchase cars with OnStar, but opt not to continue service once subscription fees begin.

Using this system, RelayRides renters can gain access to the car by having OnStar unlock the car for them and vehicle owners can earn money from otherwise idle vehicles by renting them out. Prices are set by the owner and RelayRides collects a fee for each rental. The owner does not have to be present for the renter to gain access to the car or return it.

Non-GM cars in the RelayRides program require an expensive communications device be installed. OnStar, says the peer-to-peer rental startup, gives them the opportunity to control the car without need of additional gadgets. Unlike other car sharing services like Zipcar or CityCarShare, RelayRides does not own the vehicles being rented, but instead matches car owners to renters as a go-between.

While the idea has had some pitfalls in the past, including one high-end luxury P2P car sharing company called HiGear going under after several cars were stolen through the network, it's catching on in urban environments where many car owners drive only occasionally. Insurance companies are mixed as to whether or not they oppose this idea.