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Opel to begin publishing WLTP fuel consumption numbers in Q2 2016; improving SCR for NOx reductions

Beginning in Q2 2016, and in addition to the official fuel consumption and CO2 information, Opel will start publishing fuel consumption numbers recorded under the WLTP cycle, starting with the new Astra.

In addition, Opel’s diesel engineers have recently started working on an initiative to implement NOx emission improvements on SCR (Selective Catalytic Reduction) diesel applications. This is a voluntary and early improvement towards the RDE (Real Driving Emissions) legislation that goes into effect in Europe in 2017. Opel said it is committed to providing the testing authorities transparency.

The events and discussions in the last weeks and months have shown that there is a tremendous focus on the automotive industry and it is now time to act based on the learnings. It is obvious to me that the diesel discussion is a turning point. The world is not as it was before. We cannot ignore this and it is in the hands of the automotive industry to change the perception of the new reality.

—Opel Group CEO Dr. Karl-Thomas Neumann

According to EU plans, the “New European Driving Cycle” (NEDC) will be replaced starting in 2017 with the more modern standard “Worldwide Harmonized Light Duty Vehicles Test Procedure” (WLTP). The WLTP—which, like the NEDC, is also a cassis dynamometer test—is more consistent with fuel consumption and CO2 emissions in real-life road traffic than the NEDC. This new test cycle will be important to maintain standardized, reproducible and comparable results.

The NEDC increases speed and resistance at a steady and predictable pace—nothing like driving in the real world. WLTP better mimics real driving conditions, with more modern and realistic driving scenarios. It also considers other widely used factors such as air conditioning and seat heaters that drive fuel consumption upwards. As a result, wrote Christian Friis Bach, Executive Secretary of UNECE (the developer of WLTP), the WLTP is more like running up and down in a hilly park with a backpack, rather than a predictable climb up a set of stairs.

A partial comparison of WLTP to NEDC. Source: AVL. Click to enlarge.

Estimates project that fuel consumption under the WLTP will be 10 to 20% higher than those under the current test cycles.

RDE is complementary to the WLTP, and checks emissions outside of the well-established testing procedures in labs by using Portable Emission Measurement System (PEMS) in on-road testing. The upcoming EU6c Emission Regulation will implement Real Driving Emissions as an additional type approval requirement in the 2017 - 2020 timeframe.

SCR technology. Related to NOx emissions, Opel has started working on improved solutions for the effectiveness of exhaust gas treatment systems in Euro 6 diesel engines with SCR technology to make improvements in the direction of future RDE guidelines.

Our analyses in the last months show that we have no devices that tell us if our vehicles are in a test cycle or not. Nevertheless, we also believe that we are capable of further improving the effectiveness of reduction of oxides of nitrogen emissions from our Euro 6 diesels with SCR technology and so we are making an improvement towards future RDE specifications. We will use SCR as the mainstream system for Euro 6 diesel going forward as we continue to develop improved technologies to explore higher efficiencies

—Dr. Karl-Thomas Neumann

Opel expects to implement a production implementation of the new NOx reduction work in the summer of 2016. This activity will also include a voluntary customer satisfaction field action that will involve 43,000 vehicles that are already on the road in Europe (Zafira Tourer, Insignia and Cascada). These vehicles will get a new calibration once it becomes available.

Opel CEO Dr. Neumann also called for improving the transparency between automakers and authorities in Europe. “In the USA, the companies disclose their complete calibration philosophy to authorities. I would like to see us embrace this practice in Europe.” In this context, the Opel CEO also wants to suggest that all automakers that are active in Europe take part in a negotiated agreement for more transparency.



Good for Opel. The sooner we start to use realistic mpg, co2 and NOx figures in Europe, the better.
It doesn't matter if the reported figures go up, what is important is that we get the truth.
Then we can fix real problems with a clear direction.
All the companies should voluntarily start to do this.
Nice to see some leadership from Opel.


People are entitled to the real numbers, no more self reporting by Ford and Hyundai of mileage higher than what they actually get.


It is good to see that the WLTC is going to replace the very much outdated NEDC.
I agree with what Tesla is saying, people are entitled to real numbers and hopefully good riddance to the NEDC that is riddled with loopholes allowing manufacturers to effectively doctor the results.
It seems just incredible that in 2015 a test cycle such as the NEDC still exists?
You have got to give Opel group huge credit for this, they are the first ones stepping up to the plate and hopefully continue to be transparent... the rest should follow.
Also looking at the chart provided in this article, you can see straight up why the WLTC will provide more realist mpg and CO2 results, but the interesting question here is how close to real life driving will the WLTC be? I have mentioned this a few time, but wouldn't physically driving these cars on a road or test track designed to simulate town and motorway provide more accurate results? Does anyone here know if this is just too unrealistic to do?
Finally, I wanted to share an cool infographic as to why the NEDC is such an outdated test cycle and why you should never rely on the figures provided by it. The infographic is based on Which's? findings. http://www.vanleasing.com/why-vehicles-dont-reach-mpg.html
Yes that is correct, you will be spending an average of £133 more on fuel because the NEDC will show your car 40% more fuel efficient than it actually is.....crazy

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