Except rural communities are both more car dependent than cities, and have more tightly knit communities, so isolation probably isn't just a function of owning cars. Cars are probably the wrong mode of transportation for large cities, but then the question becomes: is that how we should all live, and to what extent does a better solution for the group override a better solution for the individual? Because, like it or not, cars are a better personal solution if you aren't bumper-to-bumper in a commute. I'm not going to take my dog or my surfboard on the bus or a train, and I have a life that doesn't end at the city's boundaries.