Mark Perry’s blog (Hat Tip Greg Mankiw) graphs gasoline prices compared to average US household net worth 1947-2007. As a percentage of net worth, consuming 1000 gallons of gasoline in the US these days costs less than at any time prior to 1985. I assume, the same story for Australians. Rising wealth is insulating us from the prospects of reduced oil availability.
A discussant on Mark's blog points out that the decline in effective expense would be greater if improvements in full use efficiency were accounted for.