When evaluating landuse Efficiencies needs to have their total impact evaluated. For example saying a Prius is efficient leaves out the landuse element. A Prius is more efficient than a Ford F150 in fuel consumption; but the issue of fuel consumption arises because of the poor landuse choice of living out in what used to be the sequestered carbon of open space. Politically moving policy in favor of a Prius thus means we can continue to expand usage of air and water and food and land basins, i.e the biosphere, that we pollute.
The efficiency is thus only relative to the reduced variable of fuel consumption and not the total impact of the biosphere disruption. The sustainable state would go beyond what architect S. Mouzon called Gizzmo Green in The Original Green. Growing Cooler points out that if VMT continues to grow three times faster than population growth any improvements in fuel mileage will quickly be negated. Without a competent urban strategy gains from technological improvements will be overwhelmed by suburban inefficiencies leaving us less sustainable in the future.
A combination of strategies are necessary taking advantage of efficient building types, efficient locations, reused infrastructure, efficient goods and service movement, rebuilt carbon basins, efficient technologies, and equity efficiencies to attain a sustainable state. As Zack and Lyon say the important indicator is lower per capita resource consumption, not necessarily deploying flashy new machines.