Interested in this kind of news? Receive them directly in your inbox. Delivered once a week. Sign Up It has been known for some time that a gap exists between how much fuel a car uses on the road – and thus how much carbon dioxide it emits – and how much fuel its official data says it uses. A recent report by an independent research organisation, the International Council on Clean Transportation (ICCT), measured the discrepancy using several databases of real-world fuel consumption compiled by motorists across Europe. The ICCT analysis separates data by manufacturer and therefore makes it possible to compare the average performance of different car companies. The worst offender is the German luxury car maker BMW. Its average gap between test and real-world emissions is 30%, while at the other end of the scale, Toyota’s gap is half this level (15%). In 2005, the average difference for BMW’s was just 12%, with a 10% gap for Toyota. This suggests that the growing difference cannot be attributed to a change in driving style, but rather to further manipulation of test results by carmakers and use of technology that has a much bigger impact in the test than on the road. While BMW questioned whether the research was representative, the ICCT said its analysis was based on nearly 500 000 vehicles in Europe, both private and company cars. Data was taken from motorists’ websites in Germany and Great Britain, car drivers’ clubs in Germany and Switzerland, consumer magazines and leasing companies. Difference between car manufacturers’ test results and average real-world driving in 2011 Quite apart from the additional carbon emissions that car makers are legally obliged to limit from 2015, the discrepancy means the average car owner will spend around €300 more on fuel per year, compared with fuel consumption as stated in official data. Owners of BMW cars will have to fund about a third more fuel than is claimed in sales brochures. Vehicles are currently tested using a procedure known as the New European Driving Cycle, but it is far from new. It was developed in the 1980s and was never intended for fuel consumption testing. A new test, the Worldwide Harmonised Light Vehicles Test Procedure (WLTP), corrects many but not all the flaws in the existing test cycle. The Commission wants it to become law in the EU by 2017, and in April MEPs voted for it to be introduced then. But some national governments are seeking to delay its introduction until at least 2020, which makes the timing of this new ICCT report potentially significant. T&E has analysed the ICCT data to see how much of the improvement in emissions claimed by manufacturers between 2005 and 2011 has been delivered on the road. On average only about half (55%) of the improvement claimed in tests resulted in lower emissions and fuel consumption on the road, once again with substantial differences between car makers. If progress towards meeting the EU’s 2015 and 2020 limits is assessed on the basis of performance on the road, instead of in tests, there is a clear split between manufacturers that remain on track, and others making inadequate progress on the road. T&E’s clean vehicles manager Greg Archer said: ‘Both car buyers and those fighting climate change need reliable fuel consumption figures, but many car makers aren’t delivering. Toyota, PSA and Renault show that it is entirely possible to achieve regulatory targets on the road without cheating but others are putting more effort into cheating than reducing emissions. Europe’s officials and politicians have sent the right signal with their support of the much improved test procedure. Now EU governments need to support them to stop drivers being cheated and efforts to tackle climate change being undermined.’ The EU’s first obligatory rules on carbon emissions require carmakers to limit their average car to a maximum of 130 grams of CO2 per kilometre by 2015, and 95g by 2020. The intention is to switch to the new WLTP cycle using a conversion factor to adjust the 2020 target so that it requires no additional effort from car manufacturers, but still reflects the stringency of the original target. The Commission recently consulted stakeholders on how it propose to undertake this exercise.