Official fuel consumption values for new passenger cars in Europe are increasingly unrepresentative of real-world performance. The divergence between official and real-world fuel consumption more than quadrupled over the last fourteen years. After EU-wide CO2 standards were introduced in 2009, official values fell by 15 percent, while real-world performance only decreased by 2 percent. This divergence undermines climate change mitigation efforts and costs the average car owner €450 per year.
This study compares official fuel consumption values with actual, real-world performance for 20 popular vehicle models. Since 2009, reductions in official fuel consumption values for these 20 models range from 8 to 30 percent. On-road measurements, however, indicate that 8 of the 20 made little to no improvement in real-world fuel efficiency. Five models achieved more than a 10 percent reduction in real-world fuel consumption, relative to 2009.
The trend toward increasingly unrealistic fuel consumption values can be traced back to the exploitation of flexibilities in the current vehicle testing procedure. While the Worldwide Harmonized Light Vehicles Test Procedure (WLTP), scheduled to be introduced in the EU in 2017, will help align official and real-world fuel consumption values, it will not by itself solve the problem of unrealistic fuel consumption values. Further actions are needed, including in-use conformity testing of randomly selected vehicles on the road and the establishment of a EU-wide type-approval authority.