Mr. Mast, why is the new WLTP the right standard at the right time?

It’s good because it’s much closer to reality. The critique of the old NEDC standard was that the tests weren’t taking place under real-world conditions. Once the car was out on the road, the mileage was lower than described in the showroom. It was about bridging this gap. The testing procedures have been strengthened. When it’s all over, we simply have more realistic indications of fuel economy and emissions.


How long has TÜV SÜD been testing to this standard?

It’s been mandatory since September 1, 2017. However we’ve been using it since early 2016.


How has the workflow changed since WLTP was introduced?

The RDE measuring component out on the road was added. And we’re also now testing fully-equipped vehicles, not just the stripped-down models. We test at both 14 and 23 degrees Celsius. The cycle takes longer now, up to four weeks. The testing used to be finished in two weeks.

The NEDC standard has come under fire, particularly since the diesel emissions scandal. Does the WLTP standard remedy the problems?

As compared to the old standard, WLTP makes it much more evident when something’s wrong. For the diesel emissions scandal, the main culprit was the defeat device—which functioned perfectly on the test rollers. Now we’re also testing under real-world conditions out on the streets. The values measured will be significantly higher than the lab values and will expose any further attempts at trickery.


Why is the testing under those conditions closer to reality than any tests in a lab?

There are two aspects that play a role: firstly, environmental conditions, because if it’s cold or damp outside, then the gas mileage changes. Secondly, user behavior: if a person only drives 500 meters to the bakery and back home, that driver will have much worse fuel economy than someone who drives a lot of long distances.


How can you test for such patterns of behavior?
By really wanting to be absolutely certain and testing more than is legally required. Three examples: we also drive in reverse, turn more and change speeds more often than is required. These are optional tests for those automakers that already have successfully passed the mandatory testing and want to have even more precise data.

As of September 1, 2017, fuel economy testing according to the WLTP (world harmonized light vehicles test procedure) is mandatory for vehicle model licensing in the European Union. It replaces the previous standard, the New European Driving Cycle (NEDC). Other non-EU countries will also be using this standard, including India, Japan, Norway, South Korea, Russia, South Africa and Turkey. TÜV SÜD conducts around ten thousand tests annually at its sites in Heimsheim and Pfungstadt, Germany, and in Prague, Czech Republic.