Technical Report on the development of a World-wide Worldwide harmonised Light duty driving Test Procedure (wltp)

3Organisation, structure of the project and contributions of the different subgroups to the UN GTR

3.1WLTP Informal Group (WLTP-IG)

1. 
   Phase 1 (2009 - 2014): development of the worldwide harmonised light duty driving cycle and associated test procedure for the common measurement of criteria compounds, CO₂, fuel and energy consumption;
   
2. 
   Phase 2 (2014 - 2018): low temperature/high altitude test procedure, durability, in-service conformity, technical requirements for on-board diagnostics (OBD), mobile air-conditioning (MAC) system energy efficiency, off-cycle/real driving emissions;
   
3. 
   Phase 3 (2018 - …): emission limit values and OBD threshold limits, definition of reference fuels, comparison with regional requirements.
   

Three technical working groups were established under WLTP, each with a specific development task (see Figure ):

1. 
   the development of the worldwide harmonised test cycle (DHC) group, to develop the worldwide-harmonised Light-duty vehicle Test Cycle (WLTC), including the validation test phase 1, i.e. to analyse the test cycle and propose amendments where necessary;
   
2. 
   the development of the test procedure (DTP) group, to develop the test procedure, and to transpose this into a UN GTR;
   
3. 
   the validation task force (VTF) group, to manage the validation test phase 2, i.e. to analyse the test results and to propose amendments to the test procedure where necessary.
   

• 
  ICE-Laboratory Procedures (LabprocICE) for the development of the road load determination methods and laboratory test procedures for conventional vehicles with an internal combustion engine (ICE)
  
• 
  E-Laboratory Processes (LabprocEV) for the development of all laboratory test procedures related to electrified vehicles, including hybrids
  
• 
  PM/PN for the development of a test procedure for the determination of Particulate Matter and the Particle Number in the exhaust gas.
  
• 
  Additional Pollutants (AP) for the test procedure of currently non-regulated gaseous emission components (NO₂, N₂O, NH₃, EtOH, aldehydes, etc.)
  
• 
  Reference Fuel (RF) to define the specifications for reference fuels used in emission testing.
  

Figure : Original structure of WLTP-IG

Figure 2 shows the original road map for the development of WLTP. The development work started in September 2009.

Since the beginning of the WLTP development process, the European Union had a major political objective set by its own legislation to implement a new and more realistic test cycle by 2014⁴. This was a strong political driving factor for setting the time frame of phase 1. However, during the work of the DTP group it became clear that a number of issues, in particular but not only in relation to electric and hybrid-electric vehicles, could not be resolved in time for an adoption of the first version of the WLTP GTR by WP.29 in March 2014. Therefore it was agreed that the work of Phase 1 would be divided into 2 sub-phases:

1. 
   Phase 1a (2009 - 2013): development of the worldwide harmonized light duty driving cycle and the basic test procedure. This led to the first version of this GTR, which was published as official working document ECE/TRANS/WP.29/GRPE/2013/13 and a series of amendments published as informal document GRPE-67-04-Rev.1;
   
2. 
   Phase 1b (2013-2016): further development and refinement of the test procedure, while including additional items into the GTR.
   

Figure : Proposed structure for WLTP phase 1b

Figure : Changeover of the WLTP organization from phase 1a to phase 1b, and planning of phase 1b

The work for phase 1b was structured and organised according to the following expert groups under WLTP informal working group (see Figure and 4):

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  GTR drafting: coordination over all groups, to ensure that the GTR is robust, coherent, and consistent. This is a continuation of the GTR drafting work under phase 1a;
  
• 
  E-lab: specific test conditions and measurement procedures for electric and hybrid-electric vehicles. This is a continuation of the EV-HEV group under phase 1a;
  
• 
  Additional Pollutants (AP) for the test procedure of currently non-regulated emission components (NO₂, N₂O, NH₃, EtOH, aldehydes, etc.). This is a continuation of the AP group under phase 1a;
  
• 
  Taskforces: for each specific topic that had to be amended or be added in phase 1b, the informal working group would designate a taskforce leader, who would work in a group with interested stakeholders on developing a testing methodology and a GTR text proposal. This could be any issue related to the former DHC, LabProcICE, PM/PN or RF working groups;
  
• 
  Round Robin testing, i.e. to analyse the test results and to propose amendments to the test procedure where necessary.
  
• 
  Drafting: a subgroup has been established under the lead of the drafting coordinator and with members from WLTP leading team, Annex coordinators, Contracting Parties and NGO experts. The main tasks were a „peer review“ of the GTR, check for inconsistencies, editorial review of IWG and expert proposals.