Effect of Real World Driving and Different Drive Modes on Vehicle Emissions and Fuel Consumption 2018-01-5017

To check the regulated emission limits, mass emissions test for a vehicle is conducted on a chassis dynamometer following a driving cycle. However, the driving cycle and laboratory test are different from the real-world driving. This article presents a study conducted on a mid-size gasoline car on chassis dynamometer as well as on-road (real-world). It determines the effect of real-world driving, different drive modes (idle, acceleration, deceleration and cruising) on vehicle emissions and fuel consumption and their comparison with the laboratory data. The emissions tests were conducted on the chassis dynamometer following the Modified Indian Driving Cycle and on the selected traffic routes in Dehradun city using a Portable Emission Measurement System (OBS-2200). It was observed from the study that average on-road emission rates in gram per second were 1.35 to 2.39 times higher for CO, 1.12 to 1.39 times higher for CO₂, 2.04 to 2.32 times higher for NOx and 2.17 to 5.0 times higher for THC as compared to the chassis dynamometer test. The test results indicated that the on-road fuel consumption was higher than the dynamometer test by 22.3%, 19%, 13.9% in congested, medium and low traffic routes respectively. The low-speed conditions with frequent stop and go operation, particularly on the congested roads, were the main reasons that aggravated the vehicle emissions and fuel consumption in real-world driving conditions. The time spent in various drive modes and percentage contribution of the drive modes to vehicular emissions and fuel consumption were calculated and analyzed using a computer program developed for the study. This study was also an attempt to generate and understand the real-world vehicle emissions and fuel consumption data in a Tier-II Indian city, and to establish the correlation between the real-world vehicle emissions and emissions data generated in the laboratory as per the legislative procedure.