RDE vehicle emissions improvements assessed on a London route

Euro 5 diesel, Euro 6 PHEV gasoline and Euro 6d-TEMP diesel passenger cars have been tested for tailpipe NOx on TfL’s “West London Route”. Fast response analysers were used to correlate transient emissions with ECU data, dashcam footage and GPS information to study the vehicles’ emissions responses to stimuli from road lay-out, congestion and other real-world influences. The results show a whole route reduction of 94% total NOx for the Euro 6d-TEMP vehicle compared to the Euro 5 diesel suggesting that the turnover of the vehicle fleet and the growing proportion of improved vehicle emissions categories will, in itself, bring air quality benefits to urban areas. In addition, the particular events during the drive which produce (sometimes very short duration) spikes of NOx are analysed in terms of the engine and aftertreatment reasons for the tailpipe “event”. The main reasons for the tailpipe NOx from the three vehicles mentioned were found to be respectively: harsh accelerations, high load engine restarts and accelerations immediately following congested slow driving.