GM’s OnStar turns six million cars into potential rentals through RelayRides

Starting today, some six million General Motors vehicle owners with OnStar can rent their cars by the hour through the RelayRides nationwide car-sharing service — without having to meet the renters face to face. GM says owners could make hundreds of dollars a month, but the brave new world of street side car rentals comes with some unusual risks.

Car-sharing services such as Zipcar and Wheelz have been gaining popularity in urban areas, where many people need occasional transportation but can't justify the cost of owning and parking a vehicle. Yet the potential size of the OnStar-RelayRides network far surpasses even established rental-car firms like Hertz and Enterprise.