On-road Emissions of Light-duty Vehicles in Europe

Type approval is granted in the European Union to light-duty vehicles if these comply with emission limits during standardized emissions testing in the laboratory. Although applicable emission limits have become more stringent in past years, light-duty vehicles remain an important source of urban nitrogen oxides and carbon monoxide emissions. The persisting air quality problems suggest that standard emissions testing in the laboratory may not accurately capture the on-road emissions of light-duty vehicles. To address this hypothesis, we present the first comprehensive on-road emissions test of light-duty vehicles based on state-of-the-art Portable Emission Measurement Systems (PEMS). We find that nitrogen oxides emissions of gasoline vehicles as well as carbon monoxide and total hydrocarbon emissions of both diesel and gasoline vehicles generally stay below the respective emission limits. By contrast,However, Average nitrogen oxides emissions of diesel vehicles (0.93 ± 0.39 grams per kilometer [g/km]), including modern Euro 5 diesel vehicles (0.62 ± 0.19 g/km), exceed emission limits by 320 ± 90%. On-road carbon dioxide emissions surpass laboratory emission levels by 21 ± 9% and exceed the fleet-average emission target for passenger cars by 32 ± 20%. These findings suggest that the current emissions testing fails to accurately capture the on-road emissions of light-duty vehicles. Our research provides the empirical foundation for establishing a complementary emission test procedure for light-duty vehicles in Europe. This procedure that will be implemented together with more stringent Euro 6 emission limits in 2014. Both provisions should improve urban air quality and reinforce innovation and competitiveness of the automotive industry.JRC.F.9-Sustainable Transport (Ispra