Manufacturers plan transparency offensive –individual customer consumption ranges to be made available
The Federal Motor Transport Authority (KBA) has tested the CO2 output from diesel passenger cars made by German manufacturers and the results confirm the official values as measured on the test bench.
The KBA has investigated 19 different vehicles to determine the consumption and CO2 output of currently used vehicles when they take the laboratory test (NEDC) that has been applicable until now. The results show that except for two vehicles, the values now found by the KBA match those recorded for type approval – or in some cases are actually below them. The deviations are within the normal technical tolerances.
There are several reasons for discrepancies between the CO2 values from different measurements of the same model on the test bench. For example, the laboratory does not always provide identical boundary conditions for the different measurements, because the NEDC tests permit variables. For instance, the results depend on exactly how the driving profile is realized, e.g. precisely how the test driver steps on the gas and brake pedals. Other factors, like the ambient air or the temperature, can also lead to varying results. And the existing laboratory test does not take account of special equipment, such as the sizes of wheels and tires, or the actual vehicle weight.
That will change with the introduction of the new Worldwide Harmonized Light-Duty Test Procedure (WLTP), which is coming into force in September 2017 for new models that are up for type-approval, and in September 2018 for all new passenger car registrations. It will replace the NEDC that has been used for more than 20 years, providing a better approximation to real-world driving because it reflects today’s models and traffic situations better and also takes into account the customer’s individual vehicle with any special equipment that has been installed. Policymakers and the industry have been pushing the introduction of the new WLTP test cycle forward for several years now.
The upshot is that differences between test bench results and the values on the roads will be smaller, but will continue to exist because items such as the air-conditioning, radios, heated seats, the route profile, the driving style and the weather all affect the fuel consumption significantly. However, the WLTP cannot take all of these factors into consideration in their entirety, because only a standardized measuring procedure can ensure reproducible and thus comparable results.
For this reason, in the future the automotive manufacturers wish to offer the purchasers of new cars an individual consumption value, in addition to the WLTP value. The information will be presented as a consumption range offering the customers transparency about the range in which a certain vehicle’s fuel consumption lies. This range for the customer’s probable individual consumption will depend on a number of factors including the driving style, the route profile and the use of ancillary devices, e.g. the air-conditioning. This will give customers an additional source of information, which is intended to fill the gap that remains as a result of a standardized, representative test cycle.
Here the manufacturers have offered to play a key role in founding an institute in the form of an association that determines and indicates this consumption range in cooperation with testing organizations. Furthermore, the institute would carry out RDE measurements of pollutant emissions, first and foremost nitrogen oxides (NOx) from vehicles undergoing type approval and registration as of September 2017 on the basis of the RDE regulations that will then be in force.