Testing truck CO2 emissions
While passenger cars have long had a testing procedure, there has historically been no standard EU procedure to test new truck CO2 emissions. The European Commission has spent much of the last decade developing such a test which it has called the Vehicle Energy Consumption Calculation Tool (VECTO).
This test is an essential building block and will provide the basis for truck CO2 regulation.
What is VECTO?
Small vehicles are generally tested in a laboratory. But because of the size of trucks and the wide variety of models, laboratory testing is not really an option for large-scale testing. That’s why the Commission is following a simulation based approach. Instead of testing the whole vehicle, all components that influence CO2 or fuel economy, will be tested separately. The tyres, aerodynamics, engine, transmission, weight etc are then used as an input to a software tool that can calculate CO2 emissions over typical duty cycles. This software tool is called VECTO.
VECTO could be undermined…
In principle it is a good idea to use simulation as it allows relatively accurate calculations for a great variety of vehicles. The simulation approach has been industry practice for some time and is also used in other regions such as the US and Japan. So VECTO is a good basis for regulation. But VECTO is only as strong as the input parameters it depends on. If anything is wrong with the way aerodynamics are tested, this will have a major impact on the end result, even if the software is flawless. In that sense the truck CO2 test might be subject to the same weaknesses as the passenger car CO2 tests: lack of on-road verification testing and poor oversight and control.
What needs to be done to improve VECTO?
To make VECTO more robust a few things need to happen. First of all, the test procedure needs to be complemented by an on-road full-vehicle test at the end of the process. This test would only apply to a sample of vehicles but would be used to verify that simulated and on-road performance closely matches one another. If a truck would exceed a certain threshold or tolerance (e.g. 10%) it wouldn’t pass the procedure. This procedure is somewhat similar to the real driving emissions (RDE) procedure that was introduced to measure NOx emissions in real world traffic conditions.
Secondly, it needs to be possible for (independent) third parties to check the manufacturers test results. Currently the testing system relies on type approval authorities and technical services overseeing the tests performed by manufacturers. As the Volkswagen-affair has shown, this system is far from perfect as national type approval authorities often have a cosy relationship with manufacturers. To enable third party checking, they require full access to the test procedure and the input parameters.
