report no. 2/12

21 Feb 2012

A six vehicle study has been completed to investigate the impact of changes in thevolatility characteristics of unleaded gasoline containing 10% v/v ethanol onregulated exhaust and evaporative emissions and on hot and cold weather vehicledriveability performance. The vehicles selected for this study were representative ofthe current EU fleet, met or exceeded Euro 4 emissions certification, spanned therange from upper medium to small vehicle classes, were compatible with 10% v/vethanol according to the manufacturer’s warranty information, and included twomodern gasoline Direct Injection Spark Ignition engine types. Results includedregulated emissions measured over the New European Driving Cycle (NEDC) at+23°C and -7°C, evaporative emissions according to the European regulatoryprocedure, cold engine starting and idling at -20°C, and Hot Weather Driveabilityperformance at +40°C.Unleaded gasolines containing 10% v/v ethanol (E10 gasolines) were speciallyblended for this study to investigate changes in volatility, specifically in the E701 andE1002 distillation values. The Dry Vapour Pressure Equivalent (DVPE) of all testfuels targeted either summer (60kPa) or winter (100kPa) grade maximum values.The DVPE of the test fuel was selected to be consistent with the type of vehicle testthat was completed.To investigate the impact of volatility changes on vehicle emissions andperformance, ‘Baseline’ E10 gasolines were evaluated having E70 and E100distillation values at the current maximum limits allowed by the EN 228 gasolinespecification. Results on these ‘Baseline’ gasolines were then compared to fuelshaving relaxed volatility, that is, where the E70 and E100 values were higher thanthe maximum limits allowed by the EN 228 specification. These volatility valueswere selected based on a proposal that CONCAWE has made to the EuropeanCommittee for Standardisation to relax the volatility specifications for future E10gasoline blends.For most vehicle tests, results on the ‘Baseline’ gasoline were compared to those ona ‘Step 2’ gasoline in which the E70max and E100max specifications were relaxed by+10% v/v and +4% v/v, respectively. Some tests were also conducted on ‘Step 1’gasolines in which the E70max and E100max specifications were relaxed by +4% v/vand +2% v/v, respectively. The ‘Step 1’ gasolines were consistent with CONCAWE’sproposal to CEN for relaxed volatility specifications while tests on the ‘Step 2’gasolines represented a more severe test for vehicle emissions and driveabilityperformance.All six vehicles were able to complete the required driving cycles on all of the testfuels with no false starts, no misfires, no stalls, no failures, and no faults recorded bythe On-Board Diagnostics (OBD) systems. Overall, the impacts of gasoline volatilityon emissions and driveability performance were small compared to vehicle-tovehicledifferences.