In this study,the formula to estimate the reduction of GHG
emissions from replacing conventional petroleum fuel with biofuel
blends (RG) can be simplified as Eq. (4). Since the life cycle
assessment figures for GHG are in kilograms CO2 per kilometer
driven, we can simply calculate the decrease in CO2 emissions using
the projected consumption figures for standard gasoline, as we
assume the motor fleet must travel the same distance regardless of
the fuel it uses. The factor increase in fuel required is exactly
countered by the corresponding factor decrease in fuel economy :