Remote emission sensing compared with other methods to measure in-service conformity of light-duty vehicles: On behalf of the Swedish Innovation Agency and the Swedish Transport Administration

The emission performance of light-duty vehicles (LDVs) was investigated based on various datasets from remote sensing, PEMS and chassis dynamometer measurements. The focus of the investigation was on NOX from early Euro 6 diesels and based on three different datasets:

-        Data collected from dedicated remote sensing measurements carried out in Sweden, used to recruit vehicles for PEMS and dynamometer tests. 

-        A large remote sensing dataset from measurements carried out in six European countries, compared with a large number of PEMS RDE data.

-        Data collected by means of remote sensing, mini-PEMS and a point sampling particle number instrument at a PTI-station.  

The results of the analysis show:

-        A good agreement between remote sensing and PEMS as regards real-world NOX emission reductions from Euro 5 through the various steps of Euro 6.

-        For Euro 6ab diesel LDVs:

o      A good agreement in NOX emissions between remote sensing and PEMS with data broken down on vehicle model and engine alliance level. 

o      A reasonable agreement between remote sensing and PEMS for individual vehicles, demonstrating remote sensing capability to identify vehicles exceeding the Euro 6 NOX limit.

o      Large variations for both remote sensing and PEMS - a factor of 30-40 between the highest and lowest emitters - in NOX emissions between individual vehicles. 

-        For diesel LDV PM emissions the remote sensing data mirrors the evolution of the increasingly stricter emission standards from Euro 1 onwards, ultimately requiring newer vehicles to be equipped with DPFs, reducing real-world PM emissions by more than 90%.

-        Remote sensing can be used as a stand-alone, cost-effective method for surveying the RDE performance of the diesel LDV fleet and supplement in-use compliance programs.

-        Screening for suspected high-emitters with remote sensing and confirmatory measurements with mini-PEMS can be a potential approach to enhance PTI emission testing, e.g., by incorporating NOX and PN tests under real driving conditions.