Effect of oxygenates in gasoline on fuel consumption and emissions in three Euro 4 passenger cars

The Joint Research Centre (JRC) of the European Commission, the European Council for Automotive R&D (EUCAR), and CONCAWE jointly completed this vehicle test programme to investigate the effect of oxygenates in gasoline on the fuel consumption, regulated emissions, and particle emissions of three passenger cars homologated at the Euro 4 emissions level. Substituting oxygenates for hydrocarbons in gasoline decreases the overall energy content of the resulting blend which is also expected to increase the volumetric fuel consumption needed to achieve the same vehicle driving cycle. For this reason, a major objective of this study was to determine whether today's gasoline vehicles can improve their efficiency when running on oxygenate/gasoline fuel blends and reduce this volumetric fuel consumption penalty. In addition to a 95 Research Octane Number (RON) base gasoline, five other specially blended fuels were evaluated that varied in RON, oxygen content, and oxygenate type. Results are compared for the New European Driving Cycle (NEDC), the US06 part of the US Supplemental Federal Test Procedure (SFTP), and three constant speeds. Over all vehicle test conditions, the results show that the volumetric fuel consumption (FC) increases in direct proportion to the decrease in the fuel's volumetric energy content. Except possibly for one vehicle over one test cycle, the results show that the use of oxygenates or higher octane did not provide a volumetric FC benefit. This means that these Euro 4 passenger cars were not able to compensate for the lower energy content of oxygenated fuels through better engine efficiency for the variation in fuel properties investigated in this study.