Efficiency can in some cases be enough to achieve sustainability but not always.
No matter how efficiently you use the oil, it WILL run out.
So the actual solution is to use the natural resources efficiently and with care while we look for an alternative way that is sustainable.
And a rising price is the signal to do both.
No, because our knee-jerk reaction is to just move on to consume other stuff in the same way we did with the old stuff.