Off-cycle, Real-World Emissions of Modern Light Duty Diesel Vehicles 2009-24-0148

This paper investigates the emissions performance of modern European light-duty passenger vehicles with turbodiesel engines during real-world driving, notably during two extreme but not uncommon operating regimes: congested urban traffic and high-speed and performance driving. Four cars and one van were tested on a chassis dynamometer and/or on the road with a portable, on-board emissions monitoring system capable of online measurements of particulate and gaseous emissions. On all cars, operation at speeds and acceleration rates in excess to those within the applicable certification NEDC cycle resulted in higher concentrations of nitrogen oxide (NO) and particulate matter (PM). High-speed driving in excess of 120 km/h resulted in a marked increase in NO and PM concentrations, with further increases past 130-140 km/h. In urban driving, highest PM concentrations occurred at the onset of and during accelerations from low rpm. Aggressive, performance driving resulted in substantial increase in NO and PM emissions per kg of fuel compared to normal driving. No marked increases outside of NEDC regimes were, however, observed on the van. The results support the arguments against increase in 130 km/h freeway speed limits and for augmenting the EU certification tests for light diesel vehicles with supplemental cycles or tests.