Different driving test cycles, the Leeds-West Park (LWP) loop and the Leeds-High Park (LHP) or HPL-A and B (Leeds-Hyde Park Loop-A or B, hereafter referred as HPL-A or B cycle) loop were selected for this urban intersection research and results are presented in this study. Different emissions-compliant petrol passenger cars (EURO 1, 2, 3 and 4) were compared for their real-world emissions. A reasonable distance of steady state speed was needed and for the analysis made in this paper were chosen vehicle speeds at ~20, ~30 and ~40 km/h. Specific spot of periods of driving at the speeds mentioned above were identified, then the starting and ending point was found and the total emissions in g for that period divided by the distance was calculated. A typical urban driving cycle including a loop and a section of straight road was used for the comparison test as it was similar to the legislative ECE15 urban driving cycle. Exhaust emissions were calculated for the whole journey average and compared to EU legislation. The accumulative mass demonstrated a steady increase with time. The cold start effect was small, but there was a greater increase in CO₂ during the first 200-400 s except for EURO 3 vehicles. This effect is due to the cold lubricating oil and cold water, which give increased friction losses. The water warm up takes 200-400 s depending on the cooling system design, and this is responsible for the change in CO₂ emissions gradient. The lube oil warm up continues through the test. Lube oil and water temperature measurements for the 4 vehicles show little change in these characteristic. The improvements in CO₂ emissions with EURO 3 and 4 vehicles have to have a different source than lube oil viscosity changes with heating. Finally, objectives of this work were to address the effect of traffic situations and vehicle conditioning upon CO₂ emissions, to compare real-world emissions with some reference values such as the emission limits and to develop understanding and provide data on traffic emissions and hence air quality consequences of traffic management schemes.
SAE WC (2012)