Automobiles are the linchpin of suburbs, where middle-class families from Chicago to Shanghai tend to make their homes. And that, experts say, is a huge impediment to current efforts to drastically reduce greenhouse gas emissions from tailpipes, and thus to reduce global warming. Passenger cars are responsible for 12 percent of greenhouse gas emissions in Europe — a proportion that is growing, according to the European Environment Agency — and up to 50 percent in some car-intensive areas in the United States.

Image Cars are forbidden on most of Vauban's streets, and houses cannot have driveways or garages. Credit... Martin Specht for The New York Times

While there have been efforts in the past two decades to make cities denser, and better for walking, planners are now taking the concept to the suburbs and focusing specifically on environmental benefits like reducing emissions. Vauban, home to 5,500 residents within a rectangular square mile, may be the most advanced experiment in low-car suburban life. But its basic precepts are being adopted around the world in attempts to make suburbs more compact and more accessible to public transportation, with less space for parking. In this new approach, stores are placed a walk away, on a main street, rather than in malls along some distant highway.

“All of our development since World War II has been centered on the car, and that will have to change,” said David Goldberg, an official of Transportation for America, a fast-growing coalition of hundreds of groups in the United States — including environmental groups, mayors’ offices and the American Association of Retired People — who are promoting new communities that are less dependent on cars. Mr. Goldberg added: “How much you drive is as important as whether you have a hybrid.”

Levittown and Scarsdale, New York suburbs with spread-out homes and private garages, were the dream towns of the 1950s and still exert a strong appeal. But some new suburbs may well look more Vauban-like, not only in developed countries but also in the developing world, where emissions from an increasing number of private cars owned by the burgeoning middle class are choking cities.