Report on the development of Amendment 4 to GTR 15. Amendment 4 is part of the second phase development of the GTR mandated to:

1. Introduce definitions of response time, delay time and rise time harmonized with those in GTR Nos. 4 and 11
2. Introduce improvements to the gear shifting procedures
3. Ensure consistency in the use of the terms accuracy, precision, resolution, tolerance, repeatability and deviation
4. Address bi-fuel and bi-fuel gas vehicles in accordance with UN R83
5. Clearly define the appropriate positioning of payload mass (25 kg plus the mass of vehicle load)
6. Correct terminology such as “classes of rolling resistance coefficients”
7. Correct minor spelling and/or punctuation mistakes, and restructuring some paragraphs
8. orrect some equations and to make them all consistent with Word’s use of mathematical symbols
9. Exclude all Rechargeable Electric Energy Storage Systems (REESSs) that do not contribute to vehicle propulsion from monitoring
10. Better define the purity of certain gases such as nitrogen and synthetic air
11. Define more specifically the difference in mass of CO2 during charge sustaining between the test with the highest and lowest positive and negative electric energy charge