AECC, the Association for Emissions Control by Catalyst, conducted a test program to compare the newly developed World-harmonized Light vehicles Test Cycle (WLTC) with the current European regulatory New European Drive Cycle (NEDC) and the cold-start Common Artemis Driving Cycle (CADC).
Vehicle engines and aftertreatment technologies were selected to cover a wide range of future systems. Six European commercially available passenger cars were chosen: three Euro 5 Gasoline Direct Injection cars, two Euro 6 Diesel cars and a Euro 5 non-plug-in gasoline hybrid car. The hybrid car was tested with three different battery state of charge: nominal, minimum charge, and maximum charge.
Investigations on the test temperature were also conducted by comparing emissions at 25°C and at −7°C. Regulated gaseous emissions (HC, CO, NOx) and particulate mass and particles number were measured, together with additional pollutants such as CH4, NO2 and ammonia.
The study isolated cycle-to-cycle effects on emissions for each vehicle by normalizing the test mass in all tests to the draft WLTP (World-harmonized Light vehicles Test procedure) Global Technical Regulation (gtr). Because of the higher inertia used, emissions results obtained on the regulatory NEDC can deviate from type-approval emissions for each tested vehicle.
Comparison of emissions results obtained on NEDC and WLTC tends to show that WLTP may bring more realistic CO2 emissions from the higher vehicle inertia included in the test procedure (closer to real mass of vehicle) but most likely not from its drive cycle pattern, even if it is more transient.