In our old neighbourhood (an urban area of Toronto) we were car-free, and I'd say the average family in our area was 1-car. Some had none (but were relatively rare), some had two, and the odd family had more cars than drivers, but one was common. The main factor would be excellent access to public transportation. Most people that worked downtown would take transit to work, (a few would bike) and the ones that drove (baffle) usually both worked downtown so would drive together. Other factors are downtown parking is very expensive, and also parking spaces at people's homes was limited. Some houses had no parking (car owners would need to buy a street permit and then search for parking which was often full) and most houses had one spot. Having two or more spots was rare, and usually came at the expense of not having a backyard.

Now, we are living on an island (about Manhattan in size, but only 1200 people in population), and about 20-25 km from the nearest town of 30,000 people. Two cars is average here, and we now have one. We almost always park it at the ferry terminal off island, which has free parking, and walk (20-25 min) or bike to get to the ferry, and then choose bike, bus (only 4 times a day), or car once across. This is because it is expensive to bring the car on the ferry - some two or more-car families leave one on the other side.

Sometimes its a pain not having a car on the island - I needed to pick up a big package from the post office the other day, but I brought my bike trailer along and it fit. I work from home, my husband works in town. I think its certainly easier having one car if only one person is commuting, or if both people work the same hours and a close location.

Yesterday for example I wanted to do some shopping in town. My husband had biked to work, I walked to the ferry, then drove the car in to town to meet him when he was done, threw the bike in the back, we had dinner together, went shopping, then drove back, walked on the ferry with his bike, I had a headstart walking up the steep hill from the ferry, when we got to the top he doubled me on his rack the less than a mile of remaining distance home. Yeah I could have ridden my own bike and left it at the ferry but leaving quick I didn't want to mess with digging up a decent light (there are no streetlights for the most part here) and the rain gear.

Its a totally different world here though and its easy to be tempted to drive especially in the very rainy very windy winter. Parking is free virtually everywhere, congestion does not exist, and saving time driving on the highway versus bike can make the difference of an hour when it comes to catching the next ferry. Where living in Toronto for many of my destinations bike was faster than a car.