1. Gas fuelled vehicles in GTR 15: Bringing WLTP in line with Reg. 83:
W.F.Bill Coleman September 2017

2. Background: Regulation 83 was amended in recent years at the request of industry to permit limited operation of a Bi-Fuel Gas Vehicle either on petrol or on a mixture of petrol and the gaseous fuel when operating in the gas fuel mode. A justification for this was the cooling of engine valves during high load operation. The amendment consisted of amended definitions, introduction of additional text to the section on engine starting and the introduction of 2 appendices to calculate a so called “energy ratio”. This energy ratio describes the amount of operation on petrol in a type 1 test and may not exceed 20% in total. There has been some inconsistency in the transposition of these amendments into EU legislation and this may have contributed to the essential exclusion of this concept from GTR 15.

3. Current definitions: 2017/1151 (EU-WLTP): (11) ‘bi fuel vehicle’ means a vehicle with two separate fuel storage systems that can run part-time on two different fuels and is designed to run on only one fuel at a time; (12) ‘bi fuel gas vehicle’ means a bi fuel vehicle that can run on petrol and also on either LPG, NG/biomethane or hydrogen; ECE-R 83.07: "Bi-fuel vehicle" means a vehicle with two separate fuel storage systems that is designed to run on only one fuel at a time. The simultaneous use of both fuels is limited in amount and duration "Bi-fuel gas vehicle" means a bi-fuel vehicle that can run on petrol (petrol mode) and also on either LPG, NG/biomethane, or hydrogen (gas mode).

4. Proposed definitions: ECE-R 83. 07: 2. 23
Proposed definitions: ECE-R 83.07: "Bi-fuel vehicle" means a vehicle with two separate fuel storage systems that is designed to run on only one fuel at a time. The simultaneous use of both fuels is limited in amount and duration "Bi-fuel gas vehicle" means a bi-fuel vehicle that can run on petrol (petrol mode) and also on either LPG, NG/biomethane, or hydrogen (gas mode) "Bi-fuel vehicle" means a vehicle with two separate fuel storage systems that is designed to primarily run on only one fuel at a time, however the simultaneous use of both fuels is permitted in limited amount and duration "Bi-fuel gas vehicle" means a bi-fuel vehicle where the two fuels are petrol (petrol mode) and either LPG, NG/biomethane, or hydrogen. The title of 3.2. should then be amended to include alternative fuelled vehicles

5. Proposed Text in Technical Annex:
In Annex 6, add the text in red:
In the cases where LPG or NG/biomethane is used as a fuel, it is permissible that the engine is started on petrol and switched automatically to LPG or NG/biomethane after a predetermined period of time that cannot be changed by the driver. This period of time shall not exceed 60 seconds.
It is also permissible to use petrol only or simultaneously with gas when operating in gas mode provided that the energy consumption of gas is higher than 80 per cent of the total amount of energy consumed during the Type 1 test. This percentage shall be calculated in accordance with the method set out in Appendix 3 to this annex.

6. Proposed Appendix to Annex 6:
Regulation contains 2 Appendices to Annex 12
Appendix 1 calculates the energy ratio for LPG and Appendix 2 for NG/biomethane, these Appendices are around 98% identical
I appears therefore logical to combine these into a single Appendix to Annex 6 of GTR 15