From Wired on the future of megacities:
"It turns out that while density equals efficiency, “megacity” does not necessarily equal density. Many megacity dwellers live outside those hyper-efficient city centers, Kennedy explains. Look at New York—if you live in Manhattan or parts of Brooklyn and Queens, you’re probably getting around on the subway. But if you live in Westchester, New Haven, or Newark? You’re probably driving your car—maybe not into the city center, but around it. And there are a lot of you. That’s why New York is almost off the chart in its consumption of transportation fuel, despite all its great rail."