• English

Christian Friis Bach

Bach's Blog

The Executive Secretary's Blog

Dieselgate: Implement the new WLTP test for cars!

The story about Volkswagen and their attempt to cheat on the car test is a story of a car company wanting to keep the engines’ performance high and avoid installing expensive exhaust after-treatment technologies. However, it is also a story about a test that does not reflect the true emissions and energy efficiency of new cars. We must prevent car companies from cheating, but we must also implement a new and better test.

The good news is that a new test is ready. It has been developed under the World Forum for Harmonization of Vehicle Regulation, hosted by UNECE, and is called the Worldwide Harmonized Light-duty Test Procedure (WLTP).

The problem with the old test was that it increased the speed and resistance at a steady and predictable pace - as predictable as climbing a set of stairs - and nothing like driving in the real world.  

When we drive, we stop and go. We speed up and slow down on unpredictable cycles.  Simply put, when we drive on the road, we do not drive like we are in a laboratory.  This means that the test in the lab is easier to distinguish from real life driving and easier to cheat on.

Some argue that we should simply test cars in real life conditions on the road. However, we do need to test cars in a lab. The reason is that we need highly controlled standardized tests, where all environmental factors are exactly the same. If similar cars of two competing brands are tested in different conditions such as high wind or low pressure days, then the results will not only be inaccurate, but unfair.  One car might get a better rating because it was tested on a calmer day. 

So we need a lab test, but it must simulate the real world better. This is exactly what the new WLTP test does. It mimics real driving conditions, with more modern and realistic driving scenarios and considers other widely used factors such as air conditioning and seat heaters that drive fuel consumption upwards. It is no longer a predictable climb up a set of stairs but rather like running up and down in a hilly park with a backpack.

The WLTP also closes many of the loopholes that existed in current test methods to create more accurate, consistent and repeatable results on fuel consumption, which are also more difficult to manipulate. This means that the WLTP generates more accurate information not only on the environmental impact but also on kilometres per litre. It is estimated that the figures of fuel consumption under the WLTP would be 10 to 20% higher than those under the current test cycles. This means that when you buy a new car and see the write ups of how far you can go on a tank of fuel, it will be closer to the true consumption when you drive. The people who bought the Volkswagen cars did not just get a car that polluted more than they were told, they also did not get the petrol mileage they were promised.  Therefore, the WLTP is more reliable means of testing a car’s performance. It gives more accurate results and better information, and it is more difficult to design a defeat program for.

The WLTP is currently in the process of being implemented at UNECE. Perhaps the Volkswagen case can help to speed up the process. Implementing the new test worldwide could be a first and immediate step to creating more reliable and difficult to bypass emissions testing.

This does not guarantee that manufacturers will never beat the test again.  Given the time and resources there is no completely fool-proof test. That is why we need constant vigilance by both independent and government groups. We also need complementary tests such as the Real Driving Emissions (RDE) test, which is being developed within the EU. This test is done in addition to the laboratory test and checks emissions outside of well-established testing procedures in labs. The RDE tests will be ready for implementation early 2016.

We urge countries to increase their engagement in the World Forum for Harmonization of Vehicle Regulations (WP.29) of the Inland Transport Committee to improve and implement internationally harmonized testing procedures.

Let us work together and work fast to implement the WLTP test. The car industry must regain the trust of both consumers, car drivers and countries. And we must build and buy safer, cleaner and more energy efficient cars.


If you wonder why the animal accompanying my blog is a cow, it is because cows are fascinating animals; the cows of our host country, Switzerland, are famous for their quality; and because I am still a farmer, and miss the cows I had in Denmark. Now I got one back.