He adds: “We also found that emissions test operators struggled with the immediacy of throttle response and engine braking in a Seven. This meant that it was easy to get out of the acceptable tolerance window during the driving cycle. With NEDC, that window was visible to the tester during the test, making it much easier to follow [so a gap was rare].

“With WLTP, its not. This meant that we only knew if this had happened after the test, which invalidated the test and left us waiting days/weeks for a new test. Not because the car was failing, but because it was difficult for the human element of the test.

Lambert believes it is important that Caterham cars are clean and meet the latest standards, but points out that specialist cars cover “small mileages compared to normal road cars, so the actual annual production of emissions is a fraction of what a typical BMW or Ford could produce during a year of use.

He adds: “General legislation like this does not take into account the magnitude of the challenge for an ultra-low volume manufacturer like Caterham. To be asked to do so within the same timeframe as a large manufacturer with all its resources is unreasonable.

Why the WLTP is not really global

The objective of the World Harmonized Light Vehicle Testing Procedure, as its name suggests, is to create a global standard for emission testing. The problem is that it is neither global nor harmonized.

To begin with, North America has not adopted the system, but continues with its own CFE tests. Other countries, including important markets such as Russia and Brazil, continue to use NEDC or alternatives.

Even the regions that have adopted PMDV have adjusted it to their own needs, making it very unharmonized.

For example, with lower average speeds in Japan, your WLTP test does not include the highest speed cycle, and calculates hybrid figures differently. The result is a more accurate fuel economy figure for use in Japan, but different from Europe.

India is ready to adopt PMRV next year, but will also exclude the faster cycle due to lower average speeds, and will adopt a different reference temperature (to take into account the countrys higher average temperatures).

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