In areas such as the suburbs outlying the city, is significant infrastructure built to support the driving habit? It would be interesting to see what the correlation is between GDP growth and vehicle "support industry."
This would further prove (if the correlation exists and is positive), that we are indeed borrowing GDP growth from Mother Nature in the form of cheap gas. The scales have to balance eventually.
"The scales have to balance eventually."

This is a common, but usually wrong, way to think about things.

We have oil in the ground because the dinosaurs failed to develop a biofuel program. We are using the energy that the dinosaurs (and the rest of their ecosystem) didn't use.

Obviously, oil is finite. And we're running out of ability to increase production capacity. But where, in these statements, are the quantities that must be balanced? Where is the repayment that must be made?

Obviously, we should conserve, and we're being pretty stupid in not developing alternatives to fossil fuels. But that is not the kind of apples-to-apples comparison that you can weigh on scales.

The idea that everything is zero-sum, and anything that seems beneficial must be repaid, is--in many contexts--wrong. If you don't look at the whole system, you can't say that the system is closed or zero-sum. Our entire earth is not a closed system, thanks to the sun.

We may well overshoot and crash, but that will be more of a karmic debt than a physical debt. As long as the sun is shining, there is no law of nature that says we have to run out of energy. Imagine how much better our prospects would be if, instead of spending $200 billion on the Iraq war, we had awarded two hundred billion-dollar prizes for half-million BOEPD reductions in fossil energy use.

Chris

Perhaps commenting on our predicament in such a fashion is becoming a knee-jerk response, but we are a long way from becoming very efficient at using solar energy. Yes, the earth is not a closed system because of the inputs it receives from the sun, but at our current rate of energy demand growth, that allowance is becoming insignificant. $200 billion for solar research in the US? Heck, I'm willing to do research on it for  a few thousand, but with that kind of money, we could get every other university student to get on the playing field. More realistically, how about a "X-prize" for Solar? Set a goal of so many kW per cm2 and $10 million to the first prototype that qualifies.