Real world emissions from cars now 14% higher than official figures claim

An investigation by the research organisation International Council on Clean Transportation (ICCT) suggests that the gap between official CO2 emission figures of new ICE cars and their real-world values has increased from 8% in 2018 to 14% in 2022.

2018 marks the year in which the Worldwide Harmonised Light Vehicle Test Procedure (WLTP) – which measures fuel consumption and CO2 emissions – began to apply to all new car registrations.

a close up of a car's exhaust pipe

The ICCT compared official CO2 emission data as reported by the European Environment Agency (EEA) with real-world information from around 162,600 cars as reported by consumers on is a crowdsourced platform where users can calculate their vehicles’ fuel efficiency by logging distances driven and fuel consumption. The dataset acquired in August 2023 contains detailed records for about 1.1 million vehicles.

The results show combustion engine and hybrid cars built in 2018 had an average real-world to official divergence of 7.7%. For vehicles built in 2022, this was 14.1%.

The research focusses on nine motor manufacturers who, between them, make nearly three-quarters of the new ICE cars sold in Europe.

For 2022 cars, the highest gap was for Opel at 21%, followed by Hyundai at 20% and Ford and Seat, both at 15%. The lowest gap is Mercedes at 11%, followed by Volkswagen, BMW, and Audi, all at 12%.

On the positive side, CO2 emissions are falling. The caveat is that while the WLTP figures would have us believe that – between 2018 and 2022 – they fell by 7.3%, real-world emissions suggest that the decrease was just 2.3%.

Jan Dornoff, Research Lead at the ICCT and co-author of the report, said: ‘Our analysis shows that the real-world gap is growing again, after the introduction of WLTP. Without counteraction, official CO2 emission values will become increasingly unrepresentative of real-world values, and mandatory reductions for official values will not be reflected in the actual CO2 emissions. This will undermine the EU’s efforts to reduce transport-related CO2 emissions and result in consumers paying more for fuel than anticipated.’

Dr. Peter Mock, ICCT Europe’s Managing Director said: ‘The ICCT has been monitoring these disparities since the early 2010s, and fortunately, EU regulators now have appropriate tools to correct these divergences with transparent and reliable data. Using these tools, a correction mechanism can ensure that the CO2 emissions reduction targets that manufacturers must meet in the coming years are proportionally updated in accordance with the intended original stringency written into the law.’


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