No car ownership in 5 years here:
first it was bus everywhere, now we bike and if it's too far public transport.
Like Coffeejo; advantages of bike over bus are cost and not being bound by timetables/waiting in the rain/routes.
The only times I miss not owning a car are on the rare occasions where we want to go somewhere that's too far to cycle and requires two busses (IKEA Ashton, I'm thinking of you!) and buy something bulky; we have however brought flat-pack furniture home on the bus before...
Although, to be perfectly honest, we've only likely done this about 10 times in 5 years; and in at least three of those we bought enough stuff (from IKEA) that we just had it delivered (next day by DHL, even on Sundays!) for an extra cost. Some of it wouldn't have fitted in a 'normal' car in any case. For other shopping, you would really be surprised what you can fit onto a fully-loaded Brompton. If I needed to do more shopping and the distance wasn't an issue I'd buy a trailer.
Having the facility to hire a car if needed is something that I'd consider, but again to be perfectly honest, we would use the facility so seldom I don't think it's even worth joining a car-share scheme for us (the fact that Manchester turned down an application by one of the schemes for Withington due to the loss of a whole *two* parking spots is part of the problem, by the time you've cycled to the city centre to fetch it it makes it a bit of an expedition).
Shopping for anything else isn't a problem, my fruit/veg is either delivered or bought locally, and this happens once a week at most. Meat is delivered. Bulky groceries are also delivered. Non-food household consumables are also delivered. And all of this 'delivery' lark happens with no issues despite no-one being home to sign for things (once you've figured out which on-line shops will never listen to the 'if I'm out' instructions!).