This is a general thought on the car share idea. So where I live in WA State they tried multiple car share programs from a few companies and all of them got nowhere and they stopped it. I think in general regardless of the car brand being used it depends on the location where the car share program is happening.

For where I live life is extremely dependent on having a car and almost all households have cars and not just one but one for each driver in the household. Then comes the fact that a car share vehicle is not as readily available as ones own car; you can't go to your garage/driveway and get in the car and go. Also comes the factor of accessibility meaning how far of a distance the person has to go to reach the car share vehicle closest to them. Another point is can the car share company have all types of vehicles (sedan, suv, etc.) available in the numbers needed for that location or not.

There's also the comfort and privacy of your own car. And there's also the cost factor; for many it might just be worth more to have their own vehicle.

I think this idea just won't work for every location and never really take the place of vehicle ownership. 

if it anything like the on-demand car rental companies in my city, then it'll be really expensive.

I think this business model is intended cash in on impulsive people.