I used to live in downtown SD. It is pretty walkable but there isn’t a lot of selection for groceries. In downtown you can get by without a car most of the time if your work is downtown. North Park/Hillcrest is better IMO for life without a car, there are much better grocery stores (Whole Foods/Trader Joe’s/Henry’s as well as Albertson’s and Ralph’s all within a 1 mile radius). Post Office, drug stores, pretty much everything you need. If you worked in Hillcrest/NP or downtown you could get by with just a bike with no problems at all. I think that sort of lifestyle is going to be more and more attractive in the future.