Manipulation of fuel economy test results by carmakers: new evidence and solutions

Car buyers deserve reliable fuel consumption data as the less fuel is consumed, the lower CO2 emissions and cheaper the car is to run and often tax. A growing body of evidence shows the current test is outdated, unrepresentative of real-world driving and lax enough to allow carmakers to systematically manipulate official test results at the expense of consumers’ trust. European institutions are presently finalising a regulation to lower CO2 emissions from cars and vans in 2020. This has stimulated intense debate when and how a new official test should be introduced. This briefing informs this debate in the light of new evidence from the International Council on Clean Transportation (ICCT) that for the first time compares progress in official and real-world vehicle fuel efficiency on a brand-by-brand basis. It shows that all brands achieve less progress on the road than in the official figures. The data illustrates at present there is no level playing field and a new test is needed to provide robust data to consumers, ensure regulations achieve their objectives, and enable fair competition between carmakers.

Link to ICCT study:
Link to infographic detailing manipulations of car test:

Fig 1: Difference between manufacturers’ test results and average real-world driving in 2011 (derived from ICCT, 2013)