The CO2 divergence between NEDC correlated values – calculated via the Worldwide Harmonised Light Vehicle Test Procedure (WLTP) – and established NEDC data is "greater than expected", according to research by JATO Dynamics.

The new WLTP testing regime begins in September, applying to all newly-manufactured cars. JATO's findings, however, suggest a more significant impact on the automotive market than previously predicted.

The discrepancy in CO2 levels could result in EU fleet managers and motorists facing more taxes as vehicle data is re-homologated to WLTP standards. Vehicle manufacturers may also run into unforeseen consequences, with EU legislation penalising vehicle-makers for CO2 emissions in excess of legal targets.

With greater test numbers providing a more reliable sample size, JATO have been able to demonstrate that the difference between NEDC test data and NEDC correlated data under WLTP tests is nearly 2g/km higher than expected. Access to wider data has also allowed vehicle performance under the new WLTP test to be segmented by type.

JATO's re-homologation analysis suggests a difference of 9.6g/km in CO2 levels between NEDC and WLTP (NEDC correlated) values. These new figures are compared to the 8g/km difference provided in April 2018.  

As a result, the process of re-homologation for overall vehicle values could take longer than anticipated.

JATO predicts that once WLTP testing is enforced and more vehicle are re-homologated, CO2 values will be pushed even higher, largely due to a significant shift away from diesel to petrol vehicles within EU countries. Data from the first half of 2018 indicates a 7 percentage point increase in petrol vehicle market share, while the diesel market share fell 9 points to its lowest percentage in the last century (at 37% market share).

With CO2 emissions being a key influence on EU tax law and manufacturer penalties, the shift to WLTP test criteria could impact the industry significantly. As the WLTP correlated figures are notably higher than predicted, tax rates may be changed to accommodate the difference.

A spokesperson from JATO said: “What our latest data shows is that the impact of re-homologation to WLTP testing could be even higher than previously thought.

“As a result, car manufacturers could face a penalty of €95 per gram over the target per vehicles sold. This could amount to a huge financial penalty for the European car industry who registered more than 16 million vehicles in 2017.

“What is also worrying for the industry is that the publication of re-homologated models/versions is not progressing as quickly as expected. It has taken 11 months for 20% of existing model/versions in the market to be re-homologated and published, meaning the industry could face a backlog of vehicles that cannot be registered."

Vehicle manufacturers should take action to understand the fuel consumption and emissions values of vehicle builds according to NEDC and WLTP standards.