Usually when a stranger gets behind the wheel of your car, it's more a situation for the authorities than General Motors. But with the impending nationwide rollout of RelayRides' P2P car sharing program, owners of GM vehicles will soon be actively looking for complete strangers to take a spin at their wheels in exchange for cash. The startup, backed by venture capital from Google, launched its unique rental service two years ago in Boston and San Francisco and is now poised
