The Effect of MTBE, DIPE and TAME on Vehicle Emissions

Exhaust and evaporative emissions from seven late model cars were measured for six oxygenated test fuels and one non-oxygenated reference fuel. The test fuels contained 2.7 wt% oxygen from either MTBE, DIPE, TAME or a mixture of two or more of these oxygenates. The fuels were designed to meet 1995 RFG requirements, with nominal targets of 25% aromatics, 1% benzene and a vapor pressure of 7.5 psi. The remaining fuel properties were held constant. Vehicle emissions were speciated to determine levels of regulated air toxics, and ozone forming potentials were calculated. No differences in total VOC, air toxics or ozone forming potential were observed among the test fuels. These results indicate that MTBE, DIPE and TAME can be used concurrently and interchangeably at levels of 2.7 wt% oxygen.