Internal combustion engine

An exhaust gas control system comprising:

• an internal combustion engine having combustion chambers into which a combustion use fuel is fed for generating engine output;
• a post-treatment system arranged in an engine exhaust passage of the internal combustion engine, the post-treatment system feeding a post-treatment use fuel into the exhaust gas for treating harmful components in the exhaust gas;
• and
• an electronic control unit that controls the internal combustion engine and the post-treatment system, the electronic control unit storing (i) preset values of operating parameters of the engine such that different ones of the preset values are used for different operating states of the engine, and storing (ii) preset post-treatment use fuel feeding processes for feeding the post-treatment use fuel,
• wherein each time an operating period of the engine passes a predetermined time period, the electronic control unit (a) resets the different ones of the preset values of the operating parameters for the different operating states of the engine and (b) resets the preset post-treatment use fuel feeding processes so that a total amount of consumption of the combustion use fuel and the post-treatment use fuel per set driving distance is minimized while maintaining the amounts of harmful components in the exhaust gas discharged into the atmosphere below regulatory values.