We have vast, untapped reserves in the form of conservation.  My wife and I have been running our household much as you suggest, and we consume less than half the average amount of electricity per household in the US (avg. is about about 900 kWh, we're normally under 400) and I'm sure we have by far the lowest winter heating bills in our neighborhood.

By driving less aggressively, I gain at least 8 to 10% in fuel mileage, without spending a single cent on a new car, different fuel, or any modifications.

I plan to add a solar-powered attic fan to our house soon, to help reduce our A/C bills, and we already make good use of the ceiling fans in our living room and bed room to minimize the amount of A/C we need.  (If you have a well insulated home, you can often run the A/C to knock down the temp on the really hot and humid days, then turn it off, leave the windows closed, and use a ceiling fan to stay comfortable for a surprisingly long time.)

Yes, all of these things will take some changes to our "lifestyles", and in some cases some up-front expenditures, but big friggin' deal.  We'll adjust and we'll do much more than merely survive.  It won't be a non-event like Y2K was (at least from the public view; I have a lot of first-hand experience with the behind the scenes stuff, and it wasn't easy or pretty), but the people, like Kunstler, who are predicting gloom and doom now will look nearly as silly as those, like Kunstler, who predicted gloom and doom then.