This study assessed the on-road gaseous and particulate emissions from three current technology gasoline direct injection (GDI) vehicles using portable emissions measurement systems (PEMS). Two vehicles were also retrofitted with catalyzed gasoline particulate filters (GPFs). All vehicles were exercised over four routes with different topological and environmental characteristics, representing urban, rural, highway, and high-altitude driving conditions. The results showed strong reductions in particulate mass (PM), soot mass, and particle number emissions with the use of GPFs. Particle emissions were found to be highest during urban and high-altitude driving compared to highway driving. The reduction efficiency of the GPFs ranged from 44% to 99% for overall soot mass emissions. Similar efficiencies were found for particle number and PM mass emissions. In most cases, nitrogen oxide (NOx) emissions showed improvements with the catalyzed GPFs in the underfloor position with the additional catalytic volume. No significant differences were seen in carbon dioxide (CO2) and carbon monoxide (CO) emissions with the vehicles retrofitted with GPFs.
