In document GRSG/2013/29, the AEGPL proposed to introduce new provisions into Regulation No. 67 for preventing the flow of liquefied petroleum gas (LPG) into the petrol or diesel tank, and vice versa in order to address a potential safety risk in bi-fuel or dual-fuel vehicles. At the 105th GRSG session, Germany requested a more detailed test procedure. Therefore, this proposal responds to the German request, improves certain descriptions of requirements, and provides comments to justify the various provisions.