A low temperature combustion of extremely diluted charge enables to approach the limit thermal efficiency of a spark ignited combustion engine. Homogeneous mixture combustion with high air excess ratio, typically beyond the flammability limit of a conventional spark ignition system, enables to reduce NOx emissions in raw exhaust gas. On the other hand, the extremely lean mixture leads to a lower burning velocity, poor combustion stability, leading to high unburned hydrocarbons emissions. The paper presents an ongoing research and development activities on the scavenged pre-chamber ignition system for an automotive natural gas fueled engine. The experimental work have been performed in engine laboratory at steady state conditions on a gas engine with 102 mm bore and 120 mm stroke, converted to a single cylinder engine. The in-house designed scavenged pre-chamber is equipped with a miniature pressure sensor for detailed combustion diagnostics. The results of experiments show that the scavenged pre-chamber significantly expands the flammability limit compared to the conventional SI engine. Extremely low NOx emissions in a low load, reduce the necessity of using a special NOx after-treatment to comply with the current and future NOx emission limits. At full load operation the pre-chamber engine is able to operate with the stoichiometric mixture, compatible with a three-way catalyst. The experimental data served as a validation data for the numerical simulations. The second part present results from the coupled 1-D and 3-D numerical simulation of the flow in the pre-chamber. The main goal of the CFD simulation was a description of the fluid dynamics inside the pre-chamber (as yet without combustion), mixture distribution and assessment of the scavenging quality. The pre-chamber scavenging is analyzed in detail for various measured operating points. The outputs of the simulation also serve as a base for optimization of the pre-chamber design. It is also a valuable input for the optimal control setting to improve overall functionality of scavenged pre-chamber.