Abstract: The invention describes an internal combustion engine (14) for a vehicle (12) that comprises a fly-wheel (24) placed at the rear part with respect to the internal combustion engine (14), a cooling system (28) placed at the front part with respect to the internal combustion engine, a forced induction group consisting of a turbine (22), placed on the same side as the fly-wheel (24), and a compressor (30), placed on the same side as the cooling system (28), and a system (10) for treating the exhaust gases provided with a conduit for the inlet of exhaust gases, operatively connected to the exit door of the turbine, a conduit for the outlet of exhaust gases and a main body or shell (38) internally hollow for containing a substrate (44) through which the exhaust gases are conveyed so that they are subject to predefined chemical reactions.