"Obviously cars are useful things in that they let you basically go 'anywhere' at relatively low perceived marginal cost (one problem with the way we pay for cars is that a lot of things which are really marginal costs are perceived as fixed costs by people). I think I've been car free for about 6 years now, and where I can go reasonably is dictated by where I can walk, where there's decent public transportation access, where is accessible by a cab ride I'm willing to pay for, or what's accessible by a carshare car that I'm willing to pay for. While there isn't a perfect mapping, carshare costs make perceived fixed costs (insurance, maintenance, car payments) into marginal costs to some degree. All that makes the accessible world quite a bit smaller."
This is all true. I live in Center City, and 95 percent of what I do in town is generally in Center City. That's not all bad: There's lots to do in Center City! I like my neighborhood, and I like the neighborhoods that I can walk to in 20 minutes or less -- which is quite a huge chunk of town. But it is limited. I mostly enjoy living without the car -- and I really appreciate not having the expenses -- but the limits of my travel sometimes make me wonder if living in a big East Coast city has made me more provincial than when I was living in Kansas.