Real-world vehicle fuel consumption gap in Europe is stabilizing


For the first time in years, the discrepancy between passenger vehicle type-approval test results and in-use fuel consumption and carbon dioxide (CO2) emissions did not increase, indicating a stabilization at around 39 per cent

The average gap between official fuel consumption figures and actual fuel use for new cars in the EU has slightly decreased, to a level of 39 per cent, according to the latest update by the International Council on Clean Transportation (ICCT) to its ongoing research into vehicle fuel consumption and CO2 emissions.

"It is the first time since we began our monitoring in 2012 that we observe a slight decrease in the gap between official and real-world values, to a level of 39 per cent" says Uwe Tietge, a researcher at ICCT Europe and lead author of the study. "Until now, the gap had increased from year to year."

This latest update of the ICCT's annual real-world monitor is based on a statistical analysis of data for more than 1.3 million vehicles from eight European countries. The analysis draws on data from 15 different sources: the user websites (Germany), (United Kingdom) and (France), the fleet management and fuel card companies Travelcard (Netherlands), LeasePlan (Germany), Allstar fuel card (United Kingdom), and Cleaner Car Contracts (Belgium and Netherlands), the car and consumer magazines AUTO BILD (Germany), auto motor sport (Germany and Sweden), the vehicle testing organization Emissions Analytics (United Kingdom), the car website (Spain), the car club TCS (Switzerland), and the survey 'Mobilitätspanel' (Germany).

Despite the recent slowdown, the discrepancy between official measurements of vehicle efficiency and actual performance of new cars in everyday driving has more than quadrupled since 2001—a discrepancy that translates into €400 per year in extra fuel costs for the average vehicle. As a result, less than half of the on-paper reductions in CO2 emission values since 2001 have been realized in practice.

Manufacturers measure vehicle fuel consumption in a controlled laboratory environment. Since September 2018, a new test procedure, the Worldwide Harmonized Light Vehicles Test Procedure (WLTP), has to be followed for all new vehicles. The ICCT researchers speculate that increased public attention to the real-world performance of vehicles in the aftermath of Dieselgate may have led to the observed slight decrease in the gap between sales-brochure figures and the real world. "But it may just as well be the fact that all manufacturers have met their respective CO2 targets for the year 2015 and now have only limited regulatory pressure to reduce CO2 emission values of new vehicles, until the next set of targets applies in 2020" says Dr. Peter Mock, Managing Director of ICCT Europe.

At the end of December 2018, the European Commission, the European Parliament, and the EU member states reached a political agreement on mandatory CO2 standards for new vehicles for the years 2025 and 2030. As part of the agreement, the CO2 emission level of new cars must decline by 37.5 per cent between the years 2021 and 2030. "The EU regulators have learned from previous mistakes," comments Dr. Peter Mock, referring to the new regulation's requirement that manufacturers disclose real-world fuel consumption and CO2 emission data, gathered using on-board fuel consumption meters, for all new cars from 2021 onwards. "It is now crucial that the real-world data collected from manufacturers be made transparent to consumers as well as researchers," warns Dr. Mock. "Furthermore, the European Commission should swiftly develop a methodology to penalize manufacturers that provide unrealistically low fuel consumption data to their customers, in an effort to not only stabilize but actually decrease the real-world gap in the years to come."

From laboratory to road: A 2018 update of official and "real-world" fuel consumption and CO2 values for passenger cars in Europe
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Divergence between real-world and manufacturers' type-approval CO2 emissions for various real-world data sources, including average estimates for private cars, company cars, and all data sources.
Figure 1. Divergence between real-world and manufacturers' type-approval CO2 emissions for various real-world data sources, including average estimates for private cars, company cars, and all data sources.
Data for “all data sources”
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
8% 10% 11% 12% 11% 14% 16% 18% 20% 23% 27% 28% 33% 36% 39% 40% 39%


Dr. Peter Mock
Managing Director ICCT Europe
Neue Promenade 6, 10178 Berlin, Germany
Phone: +49 (30) 847129-102

The International Council on Clean Transportation (ICCT) is an independent nonprofit organization founded to provide first-rate, unbiased research and technical and scientific analysis to environmental regulators. The ICCT participants’ council comprises high-level civil servants, academic researchers, and independent transportation and environmental policy experts, who come together at regular intervals to collaborate as individuals on setting a global agenda for clean transportation. ICCT was founded in 2005, and has offices in Berlin and Brussels, as well as in the US and China. It is funded principally by private foundations, such as the Stiftung Mercator in Europe.