Assessment of California reformulated gasoline impact on vehicle fuel economy

Fuel economy data contained in the 1996 California Air Resources Board (CARB) report with respect to the introduction of California Reformulated Gasoline (CaRFG) has been examined and reanalyzed by two additional statistical methodologies. Additional data has also been analyzed by these two statistical approaches. Within the assumptions of the analysis, point estimates for the reduction in fuel economy using CaRFG as compared to conventional, non-reformulated gasoline were 2-4%, with a 95% upper confidence bound of 6%. Substantial variations in fuel economy are routine and inevitable due to additional factors which affect mileage, even if there is no change in fuel reformulation. This additional analysis confirms the conclusion reached by CARB with respect to the impact of CaRFG on fuel economy