At least a third of official car CO2 reductions are not real

December 24, 2012

A new report for the Commission suggests about a third of reported carbon dioxide emissions reductions from new cars since 2002 have not happened. T&E says this results in drivers being ‘cheated’ out of the benefits of lower fuel costs, as well as higher emissions of greenhouse gases.


The report adds weight to a study published earlier in 2012 that showed emissions savings recorded in Germany were only half the amount suggested by official figures.

Fears have existed for many years that what cars are officially certified as emitting and what they really emit when out on the road are very different. Past concerns focused on the appropriateness of test cycles, but the growing gap between real-world driving and test results have led to new attention on how test results are being manipulated through car makers using ‘flexibilities’ in testing procedures. 

A new report by the Dutch consultancy TNO published by the Commission last month looked at ‘manipulations/flexibilities’ in type approval testing. It says up to two thirds of officially recorded emissions can be credited to improved technologies, but at least a third (9g/km) is likely to be the result of car makers manipulating the test procedures. The report says: ‘The estimate of the potential impact of test procedure flexibilities and their level of utilisation in the 2002-10 period appears to explain the remaining gap.’

The TNO report adds weight to the conclusions of a study published in April 2012 by the International Council on Clean Transportation. It compares official test results with a huge database of real-world fuel consumption in Germany using data from the website Spritmonitor is a site that allows users to record the real-world fuel consumption of their vehicles.

ICCT compared over 28,000 records of real-world emissions with the official CO2 figures of the same vehicles. It concluded that in the period 2001-10, CO2 emissions in Germany fell officially by 15%, but drivers reported only a 7% improvement. As a result, the fall in CO2 emissions from the average vehicle between 2006 and 2010 was officially 12% (173 g/km down to 152g) but really only 6% (190g down to 179g).

T&E’s Greg Archer says: ‘It’s clear that around a third to half of the fuel economy claimed by car makers is just hot air. Car buyers are being cheated by the makers manipulating test results to achieve better fuel economy than is possible on the road. Policy makers are being cheated as regulations intended to improve efficiency are only being met in the laboratory. And the environment suffers as official statistics indicating action to reduce greenhouse gases turn out to be greatly exaggerated. This should stop, or CO2 limits should be tightened by around 10% to account for the manipulation.’

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