The Road to Decarbonization—The Case of the Polish Passenger Car Market

Road transport is a significant contributor to greenhouse gas emissions within the European Union, with Poland showing one of the most pronounced increases since 1990. Motivated by gaps in national inventories (absence of vehicle-level mileage, limited fuel/age/spatial breakdowns, and scarce real-world hybrid performance data), we develop a novel vehicle-level integration method that links administrative vehicle records with scraped online car-sale listings via deterministic and probabilistic record linkage, imputes missing mileage, and applies age- and fuel type-adjusted emission multipliers to estimate per-vehicle emissions. The approach produces high-resolution breakdowns by fuel type, vehicle age and spatial units while explicitly accounting for hybrid vehicle behavior. This study introduces a novel methodology and analytical product that can be used to estimate emissions from the entire Polish passenger car fleet and monitor decarbonization progress. Applying this method to the Polish passenger-car fleet yields total 2024 passenger-car CO2 emissions of ≈41.4 million tonnes (our estimate aligns closely with independent national figures), with diesel, gasoline and LPG/CNG accounting for roughly 38%, 47% and 12% of CO2, respectively. We find that hybrids and EVs currently cut fleet emissions by ~2.6% (CO2), but their higher utilization magnifies their effect, while vehicle ageing increases total emissions by ~1.2% per year. These results demonstrate that integrating microdata substantially improves the monitoring of decarbonization progress.