Yep. I've used Zipcar in lieu of a car before (and now own a car that I use maybe once every two weeks), but there was just enough friction due to having to walk to the nearest available car (the closest location to us wasn't always available, so we'd have to walk a few blocks further for the closest available car), having to pay for the time when the car is just parked at your destination before you return it, and not being suitable for the kind of longer range, weekend or week long trips that are a lot of what we need a car for.
If the cars were self-driving, however, that would solve the majority of those problems. No need to hike to find the closest car, it would come to you. No need to pay for the time that it's parked while at your destination, it could be used by other people, and another car could come pick you up when you needed to leave. No need to return the car to where you picked it up, it would just go back to the closest available station and they'd rebalance themselves automatically.
If the cars were self-driving, however, that would solve the majority of those problems. No need to hike to find the closest car, it would come to you. No need to pay for the time that it's parked while at your destination, it could be used by other people, and another car could come pick you up when you needed to leave. No need to return the car to where you picked it up, it would just go back to the closest available station and they'd rebalance themselves automatically.