But more GDP output with less energy is not the same thing as using less energy.

True.  However, energy/$GNP has been on a downward slide for many decades.  If the efficiency curve rises at the same or greater rate while economic growth slows, we could easily have absolute energy consumption decline during (slow) growth.

Note that only some kinds of energy are in short supply at the moment, and we can raise efficiency of some things easily.  We can boost the amount of e.g. wind power with a relatively short lead time, freeing coal and gas for other uses.  We can insulate and cut heating energy with no loss in utility.  We can stop buying Explorers and Tacomas and buy Focuses and Civics instead; at a 17-year vehicle lifespan and a bias of miles driven toward newer vehicles, doubling fleet MPG means cutting motor fuel use by perhaps 4% per year.

There has not been a single case in my lifetime where the economy has expanded without energy consumption expanding.

Oil is the biggie here; consider the amount of low-hanging fruit in transportation.

It doesn't matter how efficient we become - at least not in the short term, because we can't become highly efficient overnight - increased economic growth will require more energy.

Consider my concept, then:  instead of burning gasoline in engines at 17% efficiency, build cars as plug-in hybrids.  Efficiency under engine power goes up by a third, and 80% of their driving is done on grid power; direct fuel consumption falls by 85%.  The remaining energy (about the same 80%, due to losses) is met by burning oil in 70% combined-cycle powerplants at 55% efficiency and 30% simple-cycle gas turbine powerplants at 40% efficiency.  Total relative oil consumption is:

• 15% of baseline used directly.
• 17.3% in the CC plants.
• 10.6% in the simple-cycle plants.

Total:  42.9% of baseline.  If you get 30% of the additional grid power from non-petroleum sources like coal, wind or solar, this falls to 34.5%.

Things look almost absurdly rosy if you postulate cogenerating furnaces to generate electricity during the heating season.  There are a lot of things we could do that we are not.  Yet.

Embarking on a plan like this would lead directly to economic growth because the money that would have gone to the oil-producing countries would go instead to the battery makers, gas-turbine manufacturers, and other uses inside the industrialized countries (including our own).