Controller for vehicle and method for estimating temperature of component of internal combustion engine

A controller for a vehicle including an internal combustion engine, the controller comprising:

• processing circuitry, wherein
• the processing circuitry is configured to execute a base temperature calculation process that calculates a base temperature of a component of the internal combustion engine from information on a driving state of the internal combustion engine,
• the processing circuitry is configured to execute a correction value calculation process that calculates a correction value for correcting the base temperature from information on a speed of the vehicle,
• the processing circuitry is configured to execute a vehicle line reflection process when the vehicle including the component of which temperature is estimated is a temperature-estimated vehicle that is in a line of vehicles in order to reflect, on the correction value, a tendency of the component to be less cooled when the temperature-estimated vehicle is a trailing vehicle than when the temperature-estimated vehicle is a leading vehicle,
• the processing circuitry is configured to execute a rearmost reflection process when the temperature-estimated vehicle is in the line of vehicles in order to reflect, on the correction value, a tendency of the component to be more cooled when the temperature-estimated vehicle is a rearmost vehicle than when the temperature-estimated vehicle is not the rearmost vehicle, and
• the processing circuitry is configured to execute a component temperature estimation process that estimates the temperature of the component of the internal combustion engine by correcting the base temperature with the correction value.