Characterizing and assessing the fuel economy, particle number and gaseous emissions performance of hybrid electric and conventional vehicles under different driving modes

Abstract

Hybrid electric vehicle (HEV) is considered to be more energy efficient and less emissions than conventional gasoline vehicle (CV). A growing number of studies suggested that real-road emissions may be much higher than laboratory measurements. To compare the fuel economy and emissions performance of HEV and CV on real roads, this study conducted real driving emission (RDE) tests on HEV and CV of the same configuration under real driving conditions with aggressive and normal driving styles. The results indicated that the HEV had lower fuel consumption (L/100 km), nitrogen oxides (NOX) and carbon dioxide (CO2) emissions compared to the CV. Fuel saving of HEV compared to CV was up to 41.14% under urban conditions. Compared to emissions of other trip conditions, The CO2 and NOX reductions of HEV under urban conditions were the largest, which were more than 33.65% and 61.98% respectively. However, the particle number (PN) and carbon monoxide (CO) emissions of HEV were larger than those of CV. This was due to the frequent stopping and restarting of the internal combustion engine of the HEV. In order to comprehensively compare the fuel economy and emissions performance of HEV and CV, the evaluation index of real conformity factor was proposed. The analysis showed that to reduce the high PN and CO emissions of HEV, a combination of fuel economy-focused and emission control-focused strategies should be used.