Germany, home of the high-speed autobahn, is perhaps one of the few countries that has had as intense a love affair with the automobile as the U.S. But in an effort to go green, the country's second-largest city is studying ways to eliminate cars by 2034. The northern city of Hamburg has laid out an initial concept, named the Green Network Plan, that would expand public transportation and add more routes for pedestrians and bicyclists. The most controversial aspect of the plan calls for a steady phase-out of automobiles in the center of the city over the next two decades....