On-Road Emission Performance of Late Model Diesel and Gasoline Vehicles as Measured by Remote Sensing

A newly developed remote sensing instrument with NO2 and NOX measurement capability was operated in the fall of 2016 over 19 workdays in Gothenburg, Sweden, to measure real driving emissions from a large number light- and heavy-duty vehicles. From more than 30,000 registered vehicle passages, a final QA/QC-reviewed dataset consisting of about 15,000 paired records containing emissions, driving condition and detailed vehicle information data, was used to evaluate the real-world emission performance of in particular Euro 5 and Euro 6 diesel vehicles. More than 9,000 records were of diesel vehicles, of which about 5,500 were of Euro 5 vehicles and about 2,600 of Euro 6 vehicles. The following conclusions were made from the evaluation: - Measurements on more than 6,000 diesel passenger cars reveal that the real driving emissions of NOX from Euro 6 diesel cars on average have been reduced by about 60% from pre-Euro 6 levels, e.g. Euro 5. This may be considered a major breakthrough, since the real-world NOX emissions from diesel passenger cars have been virtually unchanged between Euro 2 and Euro 5, although the NOX emission standard has been significantly lowered from Euro 2 to Euro 5. Still, Euro 6 diesel passenger car real-world NOX emissions are roughly more than 5 times higher than the Euro 6 standard, as well as than the measured average on-road NOX emissions from Euro 6 gasoline passenger cars. - For NOX emissions, an almost identical pattern as for diesel passenger cars was observed for both diesel light-duty commercial vehicles and diesel heavy-duty vehicles (trucks and buses), i.e. virtually no change in real-world emissions between Euro 2 and Euro 5, followed by a major drop in emissions for Euro 6. - Primary NO2 emissions from diesel light-duty vehicles (both PC and LCV) have been reduced from Euro 4 through Euro 6, implying that the emission ratio of NO2 to NOX has also been reduced, but the ratio is still as high as about 25% for both Euro 5 and Euro 6 (compared to about 15% for Euro 2). The opposite pattern exists for heavy-duty vehicles, for which the NO2/NOX-ratio increased from about 10% for Euro 4-5 to ≈35% for Euro 6. - For all categories of diesel vehicles, real-world PM emissions have dropped steadily from Euro 2 through Euro 6 – reductions are in the order of 90% for Euro 6 compared to Euro 2. - For Euro 4, 5 and 6 diesel passenger cars, real-world emissions of both NOX and NO2 increase with decreasing ambient air temperature. The temperat