Factors influencing CO2 emissions in petrol passenger cars: evidence from Slovakia

    Břetislav Andrlík Info
    Michal Mádr Info
DOI: https://doi.org/10.3846/transport.2026.22871

Abstract

The aim of this article is to identify the factors that influence the evolution of CO2 emissions in gasoline passenger cars. Specifically, the factors that can be obtained during emission measurements at technical inspection stations are analysed. This identification is used to determine the factors obtained by measurements at the technical inspection stations that should be used as a design element for the taxation of petrol road vehicles in order to reduce CO2 emissions. The underlying source was data recorded by the vehicle technical inspection stations in 2019 and worked with passenger petrol cars of category M1. In total, almost 460000 passenger cars were analysed. 12 factors were used for each car, from which 7 variables were identified through 2 methods (BMA and WALS) as likely to have a statistically significant effect on the magnitude of CO2 emissions. Subsequently, the effect of each factor was determined by OLS with robust Std. Err. Our results show that the maximum engine power and the latest emission standards can be used as design element for the taxation of gasoline road vehicles, as a positive relationship between the growth of this factor and the magnitude of CO2 emissions of gasoline vehicles has been demonstrated.

Keywords:

petrol passenger cars, externalities of transport, carbon dioxide, emission factors, Slovakia

How to Cite

Andrlík, B., & Mádr, M. (2026). Factors influencing CO2 emissions in petrol passenger cars: evidence from Slovakia. Transport, 41(1), 14–24. https://doi.org/10.3846/transport.2026.22871

Share

Published in Issue
April 14, 2026
Abstract Views
95

References

ACEA. 2021. ACEA Tax Guide 2021. European Automobile Manufacturers′ Association (ACEA). Available from Internet: https://www.acea.auto/publication/acea-tax-guide-2021

ACEA. 2019. Report – Vehicles in Use, Europe 2019. European Automobile Manufacturers′ Association (ACEA). Available from Internet: https://www.acea.auto/publication/report-vehicles-in-use-europe-2019

Al-Hasan, M. 2003. Effect of ethanol–unleaded gasoline blends on engine performance and exhaust emission, Energy Conversion and Management 44(9): 1547–1561. https://doi.org/10.1016/S0196-8904(02)00166-8

Andrlík, B. 2013. Composition of motor vehicle fleet in the Czech Republic and the European Union, Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 61(7): 1969–1976. https://doi.org/10.11118/actaun201361071969

Bielaczyc, P.; Woodburn, J.; Szczotka, A. 2016. Exhaust emissions of gaseous and solid pollutants measured over the NEDC, FTP-75 and WLTC chassis dynamometer driving cycles, SAE Technical Paper 2016-01-1008. https://doi.org/10.4271/2016-01-1008

CEIC. 2026. Slovakia Number of Registered Vehicles. CEIC Data, London, UK. Available from Internet: https://www.ceicdata.com/en/indicator/slovakia/number-of-registered-vehicles

Chowdhury, H.; Alam, F.; Khan, I.; Djamovski, V.; Watkins, S. 2012. Impact of vehicle add-ons on energy consumption and greenhouse gas emissions, Procedia Engineering 49: 294–302. https://doi.org/10.1016/j.proeng.2012.10.140

Ciuffo, B.; Tsiakmakis, S.; Anagnostopoulos, K.; Marotta, A.; Pavlovic, J. (Eds.). 2016. Review of in Use Factors Affecting the Fuel Consumption and CO2 Emissions of Passenger Cars. Publications Office of the European Union. https://doi.org/10.2790/140640

Crolla, D. A. (Ed.). 2009. Automotive Engineering: Powertrain, Chassis System and Vehicle Body. Butterworth-Heinemann. 834 p.

Čechovič, T.; Kendra, M. 2019. International comparison and trend of emissions in the transport sector in the European Union and Slovakia, Transport Technic and Technology 15(2): 16–23. https://doi.org/10.2478/ttt-2019-0007

De Luca, G.; Magnus, J. R. 2011. Bayesian model averaging and weighted-average least squares: equivariance, stability, and numerical issues, The Stata Journal: Promoting Communications on Statistics and Stata 11(4): 518–544. https://doi.org/10.1177/1536867X1201100402

EC. 2017. Commission Regulation (EU) 2017/1151 of 1 June 2017 Supplementing Regulation (EC) No 715/2007 of the European Parliament and of the Council on Type-Approval of Motor Vehicles with Respect to Emissions from Light Passenger and Commercial Vehicles (EURO 5 and EURO 6) and on Access to Vehicle Repair and Maintenance Information, Amending Directive 2007/46/EC of the European Parliament and of the Council, Commission Regulation (EC) No 692/2008 and Commission Regulation (EU) No 1230/2012 and Repealing Commission Regulation (EC) No 692/2008. European Commission (EC). Available from Internet: http://data.europa.eu/eli/reg/2017/1151/oj

EEA. 2017. Air quality in Europe – 2017 report. EEA Report No 13/2017. European Environment Agency (EEA). 80 p. Available from Internet: https://www.eea.europa.eu/en/analysis/publications/air-quality-in-europe-2017

EEA. 2019. Dieselisation (Share of Diesel Cars in the Total Passenger Car Fleet) in Europe. European Environment Agency (EEA). Available from Internet: https://www.eea.europa.eu/en/analysis/maps-and-charts/dieselisation-of-diesel-cars-in-4#tab-chart_1

Einmahl, J. H.; Kumar, K.; Magnus, J.R. 2011. On the choice of prior in Bayesian model averaging. Center for Economic Research Discussion Paper 2011-003, SSRN Paper 1744912. https://doi.org/10.2139/ssrn.1744912

European Council. 2020. European Council Meeting, 15–16 October 2020. Available from Internet: https://www.consilium.europa.eu/en/meetings/european-council/2020/10/15-16

EP, CEU. 2006. Directive 2006/38/EC of the European Parliament and of the Council of 17 May 2006 Amending Directive 1999/62/EC on the Charging of Heavy Goods Vehicles for the Use of Certain Infrastructures. European Parliament (EP), Council of the European Union (CEU). Available from Internet: http://data.europa.eu/eli/dir/2006/38/oj

EP, CEU. 2019. Regulation (EU) 2019/631 of the European Parliament and of the Council of 17 April 2019 Setting CO2 Emission Performance Standards for New Passenger Cars and for New Light Commercial Vehicles, and Repealing Regulations (EC) No 443/2009 and (EU) No 510/2011. European Parliament (EP), Council of the European Union (CEU). Available from Internet: http://data.europa.eu/eli/reg/2019/631/oj

EP, CEU. 2007. Regulation (EC) No 715/2007 of the European Parliament and of the Council of 20 June 2007 on Type Approval of Motor Vehicles with Respect to Emissions from Light Passenger and Commercial Vehicles (EURO 5 and EURO 6) and on Access to Vehicle Repair and Maintenance Information. European Parliament (EP), Council of the European Union (CEU). Available from Internet: http://data.europa.eu/eli/reg/2007/715/oj

EP, CEU. 2021a. Proposal for a Regulation of the European Parliament and of the Council Amending Regulation (EU) 2019/631 as Regards Strengthening the CO2 Emission Performance Standards for New Passenger Cars and New Light Commercial Vehicles in Line with the Union′s Increased Climate Ambition. COM/2021/556 final. European Parliament (EP), Council of the European Union (CEU). Available from Internet: https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX:52021PC0556

EP, CEU. 2021b. Regulation (EU) 2021/1119 of the European Parliament and of the Council of 30 June 2021 Establishing the Framework for Achieving Climate Neutrality and Amending Regulations (EC) No 401/2009 and (EU) 2018/1999 (‘European Climate Law’). European Parliament (EP), Council of the European Union (CEU). Available from Internet: http://data.europa.eu/eli/reg/2021/1119/oj

Fiorito, G. 2017. Carbon taxes to reduce CO2 emissions from road transport in Italy: estimating and simulating province-level fuel demand, International Journal of Transport Economics – Rivista internazionale di economia dei trasporti 44(1): 137–152. https://doi.org/10.19272/201706701007

Fontaras, G.; Zacharof, N.-G.; Ciuffo, B. 2017. Fuel consumption and CO2 emissions from passenger cars in Europe – laboratory versus real-world emissions, Progress in Energy and Combustion Science 60: 97–131. https://doi.org/10.1016/j.pecs.2016.12.004

Grelier, F. 2018. CO2 Emissions from Cars: the Facts. European Federation for Transport and Environment AISBL, Brussels, Belgium. 53 p. Available from Internet: https://www.transportenvironment.org/articles/co2-emissions-cars-facts

Kok, R. 2013. New car preferences move away from greater size, weight and power: impact of Dutch consumer choices on average CO2-emissions, Transportation Research Part D: Transport and Environment 21: 53–61. https://doi.org/10.1016/j.trd.2013.02.006

Kropiwnicki, J.; Kneba, Z. 2013. Carbon dioxide potential reduction using start-stop system in a car, Key Engineering Materials 597: 185–192. https://doi.org/10.4028/www.scientific.net/kem.597.185

Magnus, J. R.; Powell, O.; Prüfer, P. 2010. A comparison of two model averaging techniques with an application to growth empirics, Journal of Econometrics 154(2): 139–153. https://doi.org/10.1016/j.jeconom.2009.07.004

Marotta, A.; Pavlovic, J.; Ciuffo, B.; Serra, S.; Fontaras, G. 2015. Gaseous emissions from light-duty vehicles: moving from NEDC to the new WLTP test procedure, Environmental Science & Technology 49(14): 8315–8322. https://doi.org/10.1021/acs.est.5b01364

Merkisz, J.; Pielecha, I.; Pielecha, J.; Brudnicki, K. 2011. On-road exhaust emissions from passenger cars fitted with a start-stop system, Archives of Transport 23(1): 37–46. https://doi.org/10.2478/v10174-011-0003-z

Mickūnaitis, V.; Pikūnas, A.; Mackoit, I. 2007. Reducing fuel consumption and CO2 emission in motor cars, Transport 22(3): 160–163. https://doi.org/10.3846/16484142.2007.9638119

Ministerstvo vnútra Slovenskej republiky. 2026. Celkový počet evidovaných vozidiel v SR. Available from Internet: https://www.minv.sk/?celkovy-pocet-evidovanych-vozidiel-v-sr (in Slovak).

Mock, P.; Kühlwein, J.; Tietge, U.; Franco, V.; Bandivadekar, A.; German, J. 2014. The WLTP: How a new test procedure for cars will affect fuel consumption values in the EU. Working Paper 2014-9. International Council on Clean Transportation (ICCT). 20 p. Available from Internet: https://theicct.org/publication/the-wltp-how-a-new-test-procedure-for-cars-will-affect-fuel-consumption-values-in-the-eu

Mossa, M. A. A.; Hairuddin, A. A.; Nuraini, A. A.; Zulkiple, J.; Tobib, H. M. 2019. Effects of hot exhaust gas recirculation (EGR) on the emission and performance of a single-cylinder diesel engine, International Journal of Automotive and Mechanical Engineering 16(2): 6660–6674. Available from Internet: https://journal.ump.edu.my/ijame/article/view/249

Paltsev, S.; Chen, Y.-H. H.; Karplus, V.; Kishimoto, P.; Reilly, J.; Loeschel, A.; Von Graevenitz, K.; Koesler, S. 2015. Reducing CO₂ from Cars in the European Union: Emission Standards or Emission Trading? CAWM Discussion Paper No. 84. Centre of Applied Economic Research [Centrum für Angewandte Wirtschaftsforschung (CAWM)], Munster, Germany. 35 p. Available from Internet: https://www.econstor.eu/handle/10419/111663

Park, C.; Choi, Y.; Kim, C.; Oh, S.; Lim, G.; Moriyoshi, Y. 2010. Performance and exhaust emission characteristics of a spark ignition engine using ethanol and ethanol-reformed gas, Fuel 89(8): 2118–2125. https://doi.org/10.1016/j.fuel.2010.03.018

Parry, I. W. H.; Walls, M.; Harrington, W. 2007. Automobile externalities and policies, Journal of Economic Literature 45(2): 373–399. https://doi.org/10.1257/jel.45.2.373

Patil, C.; Varade, S.; Wadkar, S. 2017. A review of engine downsizing and its effects, International Journal of Current Engineering and Technology (SI7): 319–324. Available from Internet: https://ijcet.evegenis.org/index.php/ijcet/article/view/4477

Pavlovic, J.; Ciuffo, B.; Fontaras, G.; Valverde, V.; Marotta, A. 2018. How much difference in type-approval CO2 emissions from passenger cars in Europe can be expected from changing to the new test procedure (NEDC vs. WLTP)?, Transportation Research Part A: Policy and Practice 111: 136–147. https://doi.org/10.1016/j.tra.2018.02.002

Pavlovic, J.; Marotta, A.; Ciuffo, B. 2016. CO2 emissions and energy demands of vehicles tested under the NEDC and the new WLTP type approval test procedures, Applied Energy 177: 661–670. https://doi.org/10.1016/j.apenergy.2016.05.110

Posada, F.; Façanha, C. 2015. Brazil Passenger Vehicle Market Statistics: International Comparative Assessment of Technology Adoption and Energy Consumption. International Council on Clean Transportation (ICCT), Washington, DC, US. 63 p. Available from Internet: https://theicct.org/sites/default/files/publications/Brazil%20PV%20Market%20Statistics%20Report.pdf

S-EKA. 2026. Interné údaje o vozidlách kategórií M, N a T z emisných kontrolných staníc na Slovensku v roku 2019. S-EKA, spol. s r.o. Available from Internet: https://www.seka.sk (in Slovak).

SRU. 2005. Reducing CO2 Emissions from Cars. German Advisory Council of the Environment (SRU – Sachverständigenrat für Umweltfragen). 48 p. Available from Internet: https://www.umweltrat.de/SharedDocs/Downloads/EN/02_Special_Reports/2005_Special_Report_Environment_Road_Transport_summary.pdf

Tanaka, K.; Berntsen, T.; Fuglestvedt, J. S.; Rypdal, K. 2012. Climate effects of emission standards: the case for gasoline and diesel cars, Environmental Science & Technology 46(9): 5205–5213. https://doi.org/10.1021/es204190w

Tsalikidis, N.; Mellios, G.; Mystakidis, A. 2020. Factors Affecting the CO2 Emissions Performance of Five EU Car Manufacturers. Eionet Report ETC/ATNI 2019/15. 57 p. Available from Internet: https://www.eionet.europa.eu/etcs/etc-atni/products/etc-atni-reports/etc-atni-report-15-2019-factors-affecting-the-co2-emissions-performance-of-five-eu-car-manufacturers

UN. 2026. Paris Agreement – Status of Ratification. United Nations (UN). Available from Internet: https://unfccc.int/process/the-paris-agreement/status-of-ratification

US EPA. 2021. The 2020 Automotive Trends Report: Greenhouse Gas Emissions, Fuel Economy, and Technology since 1975. EPA-420-R-21-003. United States Environmental Protection Agency (US EPA). 151 p. Available from Internet: https://www.epa.gov/sites/default/files/2021-01/documents/420r21003.pdf

Waldron, C. D.; Harnisch, J.; Lucon, O.; Mckibbon, R. S.; Saile, S. B.; Wagner, F.; Walsh, M. P. 2006. Mobile combustion, in S. Eggleston, L. Buendia, K. Miwa, T. Ngara, K. Tanabe (Eds.). 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Volume 2 Energy: 3.1–3.78. Intergovernmental Panel on Climate Change (IPCC). Available from Internet: https://www.ipcc-nggip.iges.or.jp/public/2006gl/pdf/2_Volume2/V2_3_Ch3_Mobile_Combustion.pdf

Zachariadis, T.; Ntziachristos, L.; Samaras, Z. 2001. The effect of age and technological change on motor vehicle emissions, Transportation Research Part D: Transport and Environment 6(3): 221–227. https://doi.org/10.1016/S1361-9209(00)00025-0

Zheng, M.; Reader, G. T.; Hawley, J. G. 2004. Diesel engine exhaust gas recirculation – a review on advanced and novel concepts, Energy Conversion and Management 45(6): 883–900. https://doi.org/10.1016/S0196-8904(03)00194-8

View article in other formats

CrossMark check

CrossMark logo

Published

2026-04-14

Issue

Section

Original Article

How to Cite

Andrlík, B., & Mádr, M. (2026). Factors influencing CO2 emissions in petrol passenger cars: evidence from Slovakia. Transport, 41(1), 14–24. https://doi.org/10.3846/transport.2026.22871

Share