I don't know how good the service is in SF, but generally I can recommend it strongly for this use case. My parents did that around 2000 for 3 or 4 years (in Ge

I don't know how good the service is in SF, but generally I can recommend it strongly for this use case. My parents did that around 2000 for 3 or 4 years (in Germany, in a bigger city). We rented a car once a week for grocery shopping and sometimes for a family trip (we even did a 2-week holiday trip with a rented car). With this usage we definitely saved money. And a lot of time, because you don't have to care about repairing the car, taxes, ... My father got a new job, moved to a small city without a car sharing service and bought a mercedes. He probably wouldn't "downgrade", but he is constantly annoyed because he has to care about all the small details (changing tires in the winter, refilling oil, then often small things like light bulbs break, ...).