Yeah, I am hoping that more expensive gas will translate to more customers, which will then mean they can keep their rates competitive despite the gas. (And maybe expand their fleet too... I'd be less happy if the handful of cars near my house became harder to reserve.)

I don't really know how much of an incentive that "free" gas is, though; I switched from car owner to ZipCar customer to save on insurance, which is horrendous in MA. I didn't even know they covered gas until I started using their service (insofar as you're actually paying them to cover it... but it's an undeniably nice feeling to go for a $10 spin and buy $30 of gas with someone else's card).