Amended Phase 2a Worldwide Light vehicles emissions Test Procedure (WLTP). Versions of the amended GTR highlighting the changes to the original regulation are available in word format and pdf format. The amendments address:

1. If an alternative value is applied for a parameter, such as a higher n_min_drive or an ASM, this parameter value has to be the same within an interpolation family (Paragraph 5.6.1.).
2. The mass in running order used for the calculation of the power to mass ratio is replaced by mass in running order minus 75 kg (paragraph 1. of Annex 1).
3. Idle engine speed n_idle is removed from the power curve measurement requirement (paragraph 2. of Annex 2).
4. The additional safety margin (ASM) value may be decided by manufacturer rather than the prescribed exponential curve (paragraph 3.4. of Annex 4).
5. The number of decimal place of road load coefficients is defined (paragraph 2.4. of Annex 4).
6. Additional restrictions are set to the application of the split run method for coastdown testing (paragraph 4.3.1.3.4. of Annex 4).
7. Specific data rejection criteria are added (paragraph 4.3.1.4.3. of Annex 4).
8. The “delta method” for road load determination is added (paragraph 6.8. of Annex 4 and other paragraphs. See section 4.4.25.for more detail).
9. The roller radius correction factor is modified(paragraph 6.6.3. of Annex 4).
10. The allowable combination of the test vehicle selection and family requirements are further clarified (paragraph 4.2.1.3. of Annex 4 and other paragraphs of Annex 4).
11. Provisions for an additional cooling fan are included(paragraph 1.1.5. and 1.1.6. of Annex 5).
12. The correction of measurement/recording frequency requirements are specified (over several annexes).
13. Calculation of the n/v ratio is defined (paragraph 8. of Annex 7).
14. The stepwise procedure for calculating the final test results of OVC-HEVs is added (paragraph 4.6. of Annex 8).