I lived in European capitals for 15 years and got rid of my car after the first few. It was more of a burden than a positive contribution to my quality of life. My bike certainly amortised itself... and not even against the potential ownership of a car, but simply against public transport, which is good but expensive in London. The last years, I subscribed to a car share club scheme that let me take out a small car whenever I needed one for a very reasonable price and rented one if I needed one for a few days at a time, or for a trip outside the country. Easy.

Now it's unhelpful to be too ideological about it. Now that I live in Alaska, I have my own car, and it's a big one (for me -- a small 4WD SUV). I balk at some of the cost, the low fuel efficiency (compared to what I'm used to), but living 25 miles outside Fairbanks, in a place that gets really difficult road conditions several times a year, this is appropriate right now. It's of course a choice to live that far out. Fairbanks itself is, for an American city, surprisingly cyclable. There's an acceptable network of bike path and a lot of intrepid cyclists, the university has a bike lending scheme (and offers excellent bike maintenance classes, which I'm currently taking) etc. But the temperature falls below -20°F/-30°C every winter for stretches of time, so only the most intrepid will cycle then. So I do see somewhat less serious cycling-for-transport (to the stores, with a child trailer...) than I would in a similar-sized place in Germany, even though it has its fans. Instead, it's easy to find organised club rides at non-racer level.