This page contains the most Frequently Asked Questions regarding CO2MPAS model, regulation and inputs.

For more questions, please visit: https://github.com/JRCSTU/CO2MPAS-TA/wiki/FAQ


Is the use of CO2MPAS correlation tool mandatory for all light-duty vehicles?

No, the use of CO2MPAS is not compulsory for hybrids and plug-in hybrids, double testing is allowed instead. For all the other technologies, the use of the correlation tool is mandatory. For more information and updates please see refer to point 3 of DG CLIMA’s note.

Where can the user download the latest version of the CO2MPAS?

To download the CO2MPAS latest version click here. To be notified of every CO2MPAS release, watch our GitHub repository.

Is CO2MPAS free and will it be in the future?

CO2MPAS is and will be free. To maintain it under the current EUPL license, any modifications made to the program, or a copy of it, must be licensed in the same way: EUPL.

What is CO2MPAS physical background and which formulas are applied?

CO2MPAS is a backward-looking longitudinal-dynamics CO2 and fuel-consumption simulator for light-duty M1 & N1 vehicles (cars and vans). To check the formulas the user can visit the functions’ description pages.

Where can the user find information on the status of the validation?

Detailed validation reports are provided together with every release of CO2MPAS in the validation chapter of the wiki. Here the latest 3 reports:

Validation is performed as well by independent contractors (LAT) of DG CLIMA. Moreover, some stakeholders have conducted independent validation tests on real cars in collaboration with the JRC. The results of these tests have been included in the above-mentioned reports as “real cars”.

Where can the user find CO2MPAS workshop material?

Workshop material is always uploaded in the presentation chapter.


What is the difference between Type Approval mode and engineering mode in CO2MPAS run?

In Type Approval mode CO2MPAS simulates the NEDC CO2 emission of the given vehicle fully aligned to the WLTP-NEDC correlation Regulation. If CO2MPAS finds some extra input it will raise a warning and it will not produce any result. The same will happen in the case of missing inputs. The engineering mode provides the user with full control of the tool. By using the engineering mode, all the running flags become available to the user. Moreover, the user can provide additional inputs beyond the declaration ones and check their effect on the NEDC CO2 prediction.

What is the Data synchronization tool and how does it work?

Synchronization of data from different sources is essential for robust results. CO2MPAS syncing tool uses a common signal as a reference. To avoid time-aligned signals, we advise using the velocity present on the dyno and the obd at the same time. syncing tool will shift and re-sample the other signals according to the reference signal provided. The user is allowed to apply different ways of re-sampling the original signals. For more information, please see the instructions.

What is the model selector?

CO2MPAS consists of several models. If the user provides both WLTP-H and WLTP-L data, the same models will be calibrated twice, according to the data provided by each configuration. If the option model selector is switched on, CO2MPAS will use the model that provides the best scores, no matter if the model was calibrated with another cycle. For example, if the alternator model of the High configuration is better, the same model will be used to predict the Low configuration as well.

Is it possible to simulate other cycles than NEDC or WLTP? How about real on-road tests?

Yes, CO2MPAS can simulate other cycles, as well as on-road tests. The user can simulate using several extra parameters beyond the official laboratory-measured ones. The user can input the velocity profile followed, road grade, extra auxiliaries losses, extra passengers, different road loads, temperatures, etc. The user will find an example file when downloading the demo files.

Is the usage of internal / development signals allowed (if equivalence is shown)?

OBD signals are regulated and the only one to be used.

What is the start-stop (S/S) activation time? What might happen if the user declares it wrong?

S/S is the time elapsed from the beginning of the NEDC test to the first time the Start-Stop system is enabled, expressed in seconds [s]. S/S is one of the variables that are subject to verification in case of random testing. If during verification test (random test) S/S activation time declared in CO2MPAS is lower than the span between the beginning of the NEDC test and the first engine stop, that will result in Verification Factor equal to 1 and this will have implications on the entire fleet of the specific vehicle manufacturer.

How to insert a new drive_battery_technology for hybrid electric vehicles?

For TA: the parameter already contains a preselection of drive batteries technologies as a drop-down menu. If you need to insert a different technology, please contact us at jrc-co2mpas@ec.europa.eu.

For non TA: the parameter already contains a preselection of drive batteries technologies as a drop-down menu. If you need to insert a different technology, you should remove the “data validation rule” of the excel input file, insert the new data and proceed with the co2mpas run.


Where to find the correlation regulation?

Below some useful links:

Should CO2MPAS be used for each car or each family ID?

For each interpolation family ID (IFID). Vehicle-H and Vehicle-L are utilized to define the interpolation line of Interpolation Family ID.

Is it possible to do a physical test instead of accepting CO2MPAS results?

Yes, there are cases when CO2MPAS results can be discarded and a physical test can be performed instead. For more details, check Annex I, 3.2.2.

What is DICE and who should use it?

DICE is the tool assigning a random number to each IFID type approved. It is used only for type approving purposes, by designated users.

What are the verification and deviation factors, and when do they need to be recorded?

These values need to be recorded when the random number is 90, or above, and the CO2MPAS deviation is LESS than 4 percent. For more details please refer to the correlation regulation.