It's to keep liability down. The insurance pool that ZipCar benefits from would be significantly skewed towards youth and impacting the majority of their client

It's to keep liability down. The insurance pool that ZipCar benefits from would be significantly skewed towards youth and impacting the majority of their client base to generate more credit-risk revenue is not part of the model. An 18 year old is at least twice as expensive as a 40 year old business man when it comes to car insurance.