Gasoline Direct Injection Particulate Study

Report no. 10/16: Two modern Gasoline Direct Injection (GDI) light duty vehicles have been tested to investigate the effect of oxygenates (mainly ethanol) on particulates - both mass and number, fuel economy and regulated emissions.

The GDI vehicles used in this study met Euro 4 and Euro 5 emissions limits and were tested over the New European Driving Cycle (NEDC) using ethanol containing gasolines at different oxygen levels and RON values. An ether-containing blend was also tested for comparison. Both matched RON and oxygen content ethanol and ether blends were specially prepared and tested as well as splash blended ethanol
containing fuels. Fuels were tested in duplicate using a randomized test order in order to improve statistical certainty. A rigorous test protocol was used to allow the vehicle to adapt to each fuel and reduce carryover effects.

This report gives the results of this testing and makes some conclusions on the effect of matched and splash-blended oxygenates on particulates - both particulate matter (PM) and particulate number (PN). In general fuel effects were small compared to vehicle to vehicle effects and did not affect the vehicles ability to meet the legislated specifications. Some individual observations were made in one vehicle where PN
reduced with ethanol levels at >3.7 mass% oxygen compared to lower levels and fuel consumption debits were observed in both vehicles although the low levels of PM produced by these modern vehicles made it difficult to come to any conclusions on fuel effects on this parameter.