Real-World Car Emissions Exceed Official Levels, EU Data Shows
Recent data collected by the European Commission reveals significant discrepancies between official CO2 emission figures and the actual emissions from vehicles on the road. The analysis, based on data from on-board fuel consumption monitors installed in millions of vehicles, confirms that real-world emissions for petrol and diesel cars are, on average, roughly 20% higher than indicated by standardized tests. This gap has remained consistent across the two years monitored.
Image: A car emitting exhaust fumes.
Data Collection and Scope
The data, recorded in 2022 and reported to the Commission in 2023, comes from fuel consumption monitors in vehicles first registered in the EU during 2021 and 2022. The sample includes 2.2 million vehicles registered in 2021 and 740,000 registered in 2022.
Since January 2021, new liquid-fuel cars and vans must be equipped with on-board fuel consumption monitoring (OBFCM) devices. These devices record fuel/energy consumption and total distance driven. Manufacturers must then transmit this data to the Commission annually.
Conventional Vehicle Results
For cars registered in 2021, the average gap between real-world and official CO2 emissions was 19.8% (1.2 l/100km or 28 g CO2/km) for petrol cars, and 18.2% (1.1 l/100km or 28 g CO2/km) for diesel cars. Data for cars registered in 2022 showed a similar trend: an average gap of 21.1% for petrol cars and 17.1% for diesel cars.
The Commission anticipated these discrepancies due to factors not fully replicated in laboratory tests. These factors include road conditions, landscape, ambient temperature, the use of air-conditioning and onboard electronics, and driver behavior.
Plug-in Hybrid Concerns
The data also highlights continued issues with plug-in hybrid electric vehicles (PHEVs). For PHEVs registered in 2021, real-world CO2 emissions were 3.5 times higher than laboratory values. Despite larger batteries and longer electric ranges in the 2022 models, the gap remained, suggesting PHEVs are not driven electrically as often as expected.
Future Actions
The Commission has already begun to address the issue, introducing changes to the utility factor calculation used in official test procedures. These changes, which determine the expected share of electric driving based on electric range, will be implemented in stages from 2025 and 2027. The Commission will also continue monitoring data to determine if further adjustments are necessary. The European Environment Agency has published an overview of the findings, including manufacturer-specific data.
