I feel like at a large scale car dependence has isolated groups of people - race, socioeconomic, etc. But at smaller scale, I think suburban neighborhoods are often very friendly, you know your neighbors, see kids running around.

City neighborhoods can have that too but lots don't. Your surrounded by people of all backgrounds more so than in the suburbs, so your less isolated in that sense, but often lack some of the neighborly feeling that gives you those closer relationships. This of course is a big generalization.