Based on recent research, this timely study analyzes projects and policies that might reduce greenhouse gas emissions and lessen the impact of automobiles on the environment. More than 20 transportation policy scenarios are studied, including the cost of parking, freeways, and fuel taxes; the deregulation of land-use policies; investment in public transportation, ride-sharing, and high-occupancy vehicle lanes; accommodation for bicycles; workplace and commuter choices; intelligent transportation systems; and new policies for heavy-duty vehicles.