The waste derived syngas allows the recovering of its energy using conventional technologies of energy production like internal combustion engines. However, its major drawback is its low calorific value and low stoichiometric air fuel ratio leading to higher specific fuel consumption and difficulties when using injection mode due to the required long injection duration. Recently, many studies aimed to improve the calorific value of the syngas, either by enriching it with methane or by optimizing the production techniques and the used feedstock like the refused derived fuel (RDF). Syngas produced by the pyrolysis of RDF is a methane rich syngas (40-60%) with a relatively high calorific value and stoichiometric air fuel ratio. This work is an experimental study on the combustion, performance and emissions of this type of syngas in spark ignition engine taking into consideration its composition variability. Pure methane was also tested and is considered as a reference fuel for comparison. The results show a faster and smoother combustion of syngas, lower emissions of total hydrocarbons, and higher emissions of nitrogen oxides and carbon monoxide. Beside, syngas improved the brake thermal efficiency while still maintaining higher brake specific fuel consumption with respect to methane.