Wow if only not owning a car worked outside of a city. Except it doesn't, even in the city, if you have family outside of the city how do you visit them? Would you rent a car or have someone make the trip to get you?
On your other question, I was a carless city dweller for many years. And yes I would fill in the blanks with rental cars on occasion.
Alternately, the densest cities can allow for a car-free lifestyle with rentals for out-of-town trips. However, the costs might be the same as owning a standard sedan. ($30-40k). I won't consider this bottom of the barrel at all.