The challenge of de-carbonization is one of the hot topics of today's society. The automotive field, being one of the most affected sectors by this policy, has always been involved in the pursuit of higher efficiency solutions, especially for what concerns the energy production, and the development of new technologies has been a key point in the last years. The free-piston engine linear generator (FPELG) technology has caught the attention of the research community thanks to its potential in terms of efficiency, emissions and versatility. Compared to traditional rotational internal combustion engines, it lacks the complexity of the crankshaft and connecting rod mechanism, which is also responsible for high friction losses due to the thrust forces pushing the piston against the cylinder liner.