The objective of the paper is directly related with a worldwide reality knowing that many European capital cities, such as Paris, Madrid and Athens, want to be free from automotives equipped with diesel engine by year 2020 because of pollution issues, since the C40 Mayors Summit 2016 takes place. According to the report on the Future Transport Fuels of European Commission for the year of 2050 regarding the Road transport, the use of synthetic fuels or paraffinic, methane or LPG becomes a necessity. The objective of the paper is to design and develop a Liquid Petroleum Gas (LPG) fuelling system for automotive modern diesel engine in order to assure the improving of pollution performance. The effects of LPG use at a 1.5 DCI automotive diesel engine of Dacia Logan MCV van at the regime of 40% engine load and 3900 rev/min are presented. The dual fuelled engine performance, in terms of pollutant emissions level and brake specific energy consumption, or in-cylinder pressure parameters are analyzed and compared with diesel fuel operation. By the analysis of the experimental investigation results the maximum LPG cyclic dose can be established in order obtain the highest engine performance at dual fuelling.