I think this is the case: In the fifties, there were a lot fewer people who were as rich as your dad, than there are people today who are as rich as you. At the

I think this is the case: In the fifties, there were a lot fewer people who were as rich as your dad, than there are people today who are as rich as you. At the same time, more people today want and can afford cars and other expensive things. Thus, even though we are constantly using resources more efficiently, you are competing with more people for resources today than your father in the fifties. This is natural and a good thing: If Earth can't sustain very many people buying cars every 2 years, then we can't buy new cars every 2 years. We have to use resources more efficiently. It's a similar situation with fuel: For a long time, we built stronger engines that consumed the same amount of fuel, instead of building engines that used less fuel for more efficient use. Later that trend reversed. A similar thing happened with computers and their energy use. I hope my kids won't have to buy more than one car in their life.