Middle class :)

I was reading Paul Krugman's syndicated column in the hindu this week, when i ran into an interesting issue. The columnist was (with ref to US auto workers) refering to the auto industry employment pattern and observing that it allowed "industrial workers to enjoy a middle class life style". What is interesting is how " middle class" is defined. If the class is defined by its energy consumption, the western middle class is probably on the apex of the consumption charts. If the rest of the world aspires to the same level of energy consumption, i guess we need 10 more earth's to supply the materials.