Many loopholes in testing system

Tests and real world driving differs substantially. Photo: © ra2 studio -

European carmakers manipulate emissions testing, so cars on average show 38 per cent lower emissions than under actual driving conditions.

Differences in CO2 emissions between test results and real-life driving have increased in recent years; in 2001 the gap was 8 per cent and in 2013 it had risen to 31 per cent for cars sold to private individuals. For company cars the difference was even larger, at 45 per cent. The average gap is now 38 per cent.

The EU CO2 rules for cars, which require carmakers to produce cars that on average do not exceed a certain level of CO2 per km, were adopted in 2009. However by manipulating testing, instead of investing in true technology improvements, half of the gains achieved since 2008 is actually hot air. There are substantial differences between carmakers. General Motors is the worst offender, with less than 30 per cent of claimed emission reductions actually delivered on the road. Daimler is also among the worst, with barely 40 per cent of the claimed progress reflected in real driving conditions. At the other end of the scale, Fiat and BMW deliver more than 80 per cent.

The loopholes in the testing system undermine the CO2 rules for cars, which in the end lead to higher CO2 emissions and delayed advancements towards low-carbon technology.

Furthermore, it becomes more difficult for car buyers to make informed choices in terms of fuel efficiency. There is also the risk that the consumer-driven technology development will subside.

The weaknesses of the current testing system are several:

  • The test cycle used is thirty years old and no longer representative of modern driving. For example, it contains only conservative accelerations and moderate speeds.
  • The test procedures contain many loopholes that carmakers are increasingly exploiting.
  • The carmakers use specially prepared prototype cars. This can mean tires with low rolling resistance, special lubricants in the engine for increased efficiency and a minimal interior in the car to reduce weight.
  • During the test, accessories such as air-conditioning and media systems remain switched off.
  • The test exaggerates the benefits of new technologies, such as stop-start, since the car is stationary for 20 per cent of the cycle.

A first step would be to introduce the new global Worldwide Harmonised Light Vehicle Test Procedure (WLTP), which better replicates real-world driving. The European Commission and the European Parliament have already proposed that it should be introduced in 2017, but several member states (under pressure from carmakers) want to delay its introduction.  

Greg Archer, T&E Clean Vehicles manager, said: “Unless Europe introduces the new global test in 2017 as planned, carmakers will continue to cheat laws designed to improve fuel efficiency and emissions reductions. The cost will be borne by drivers who will pay an additional €5,600 for fuel over the lifetime of the car compared to the official test result.”

But it is difficult to design tests that fully reflect reality. Also the WLTP is estimated to show about 15 per cent better results than on the road. In order to provide robust data for labelling (which can also be used as a basis for differentiated vehicle taxes), the WLTP test value needs to be supplemented with data on emissions from energy-intensive components such as lights, air conditioning and heating. One way forward according to T&E would be to update the EU Car Labelling Regulation from 1999.

Another major problem with the current system is that the organisations performing the testing services are paid directly by the carmakers and are not therefore independent of the industry. As a result they end up competing by helping their customers to find the best ways to cheat the system. The introduction of a European Type Approval Authority would ensure that tests are performed consistently and independently.

Kajsa Lindqvist

Manipulation of Fuel Economy Test Results by Carmakers: Further Evidence, Costs and Solutions. Transport & Environment, November 2014.


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