The Urban Land Institute has a new report out arguing that reducing the amount of miles driven every year is absolutely critical to reducing greenhouse gas emissions and mitigating climate change. They urge a smart growth (although that phrase seems to have faded somewhat in the jargon fad pool) strategy of bringing people closer to where they work, shop and play. Another word for that is density.
City policy is already moving in that direction, with a goal of 'driving' density to areas near subway stops. That may be problematic for under-served areas, such as Queens, where bus is the major form of mass transit. The MTA is now experimenting with bus rapid transit, to address this need.