VEHICLE CONTROLLER, VEHICLE CONTROL SYSTEM, AND LEARNING DEVICE FOR VEHICLE

A vehicle controller includes processing circuitry and a storage device. The storage device stores relationship specifying data that specifies a relationship between a state of a vehicle and at least one action variable. The at least one action variable is a variable related to operation of an operating unit of an internal combustion engine. The processing circuitry is configured to execute an obtaining process that obtains a state of the vehicle, an operating process that operates the operating unit based on a value of the at least one action variable, a reward calculation process, an updating process that updates the relationship specifying data, and a determination process that determines whether the internal combustion engine has deteriorated. The determination process is executed on condition that at least one of the at least one action variable equals a predetermined value.