Vehicle manufacturers could find ways around the new emissions testing systems introduced in the EU, warns the European Court of Auditors.
While they say EU laws on vehicle emissions have improved since the dieselgate scandal, they highlight a number of challenges facing the new system of testing.
Discrepancies between vehicle emission levels in the laboratories and on the road were brought into focus in 2015, which revealed some carmakers were using so-called “defeat devices” to produce significantly lower emissions during official tests compared to normal driving on the roads.
The Auditors warn while the scope for car optimisation has been narrowed and the European Commission’s recent legislation provides for better monitoring of the gap between laboratory figures and CO2 emissions on the road, manufacturers may find flexibilities in the laboratory tests to lower their emissions.
The report states: “There is a risk that manufacturers optimise vehicles for the RDE [Real Driving Emissions] test and that NOx emissions outside the RDE boundaries remain high. Testing cars in circulation beyond RDE parameters may address this risk.”
It adds while more than 10 million vehicles of different brands have been recalled, the limited data available indicates the impact of NOx emissions has been small.
The Auditors also suggest the new test has led to a “significant reduction” of NOx emissions by new diesel cars, however, the impact could have been greater if the initially proposed temporary limit of 128mg/km had been adopted instead of 168mg/km.
They also believe the different Euro emissions standards (from Euro 1 to Euro 6) are “not a reliable proxy” for determining car NOx emissions on the road. Although data for some diesel vehicles (mostly Euro 5 and 6) is available from various sources, comprehensive data on emissions on the road is not readily available at EU level. This hampers any potential initiative aimed at removing the more polluting cars from circulation.
The report adds the scope for independent third-party testing may be limited because of the high costs involved.
It states: “Less costly options of measuring vehicle emissions are available, such as exhaust emissions measurement using remote sensing equipment or real driving tests with SEMS [Smart Emissions Measurement System] units. While these measurements can be less accurate, they are usually sufficient to identify vehicles significantly exceeding the legal emission limits and thus needing further testing.”
The Auditors also believe the effectiveness of the market surveillance checks will depend on the set up and implementation by member states.
The report goes on: “Car drivers wishing to improve their car’s performance, to reduce consumption or to avoid expensive maintenance costs can tamper with their vehicles’ emissions after-treatment systems, similar to heavy-duty vehicle operators. This can cause the cars to emit various pollutants at levels many times above the legal limit, greatly affecting urban air quality.
“For instance, cars whose diesel particulate filters (DPFs) have been removed can emit between 20 and 50 times as much PM as cars whose DPFs are working as intended. As the problem with tampering does not fall within the remit of type-approval, in-service conformity, or market surveillance, it is for Member States to deal with it under national law.”