Altitude simulation for vehicle emissions testing : new tool for market surveillance of motor vehicles

As a follow-up of the Diesel gate scandal in 2015, EU legislation has been strengthened with the aim of reinforcing the testing procedures, and reducing the risk of presence of so-called defeat device. The updated Regulation (EU) 2018/858 define the obligation of the car manufacturers to provide to the type approval authorities a description of the emission strategies implemented in their vehicles. The verification of the absence of defeat device is done through the review of the declarations of the car manufacturers. This verification can be complemented by specific testing designed to apply the conditions in which potentially polluting emissions strategies are triggered. These conditions encompass environmental conditions encountered during the driving, like the temperature or the altitude. This report presents the very first results obtained with an Altimetric Constant Volume Sampler (ACVS) installed at the Joint Research Centre (JRC). The system simulates driving at different altitudes through changes of ambient temperature, humidity and pressure conditions at the vehicle's engine air intake and tailpipe. It aims at increasing the technical capacity of the JRC to strengthen its tasks within the market surveillance of light-duty vehicles according to Regulation (EU) 2018/858. This new facility will support the verification of the environmental performance of light-duty vehicles, and the identification of Auxiliary Emission Strategies (AES). Based on the testing of three vehicles featuring different engine technologies, the performance of the ambient conditions simulations was very good, with an average Root Mean Square Error (RMSE) ranging from 1.4 m to 2.7 m for the altitude, from 1.2% to 4.2% for the relative humidity, and from 0.2°C to 1.1°C for the temperature. In addition, the measurement performance of the different instrumentations of the new facility were found accurate and consistent. The first results of the application of the altimetry simulation for the detection of defeat devices, and for the implementation of road to laboratory testing were promising, and thus open the path to more detailed and tailored AES investigation in the future. This new testing facility can fully support research activities as well as the detection of potential defeat devices, promoting this way cleaner vehicles on the road and better air quality.