An automotive arithmetic system mounted on a motor vehicle, the automotive arithmetic system comprising: a main arithmetic unit that estimates a vehicle external environment including a road and an obstacle based on an output from a vehicle external information acquisition device that acquires information of the vehicle external environment, and generates a travel route of the motor vehicle based on the estimated vehicle external environment; an auxiliary arithmetic unit that estimates the presence of the road and the obstacle based on the output from the vehicle external information acquisition device according to a predetermined rule without using deep learning, and generates a rule-based travel route in a free space on the road where no obstacle is present; and a safe route generation unit that generates a safe route, which is a travel route that the motor vehicle takes until the motor vehicle stops at a safe stop position that satisfies a preset criterion, based on the output from the vehicle external information acquisition device without using deep learning, characterized in that the main arithmetic unit uses deep learning, the main arithmetic unit, the auxiliary arithmetic unit, and the safe route generation unit are independent from one another, and each independently execute arithmetic to generate the routes, and the automotive arithmetic system further includes an override processing unit, and based on a state of the vehicle received from a vehicle internal information acquisition device acquiring information about the state of the vehicle, the override processing unit prioritizes one of the travel route generated by the main arithmetic unit, the rule-based travel route generated by the auxiliary arithmetic unit, and determines a target motion of the motor vehicle so that the motor vehicle travels on the prioritized route, in a normal operation mode in which a failure of the vehicle has not been determined, and prioritizes the safe route generated by the safe route generation unit, and determines a target motion of the motor vehicle so that the motor vehicle travels on the safe route in a safe operation mode in which a failure of the vehicle has been determined. a main arithmetic unit that estimates a vehicle external environment including a road and an obstacle based on an output from a vehicle external information acquisition device that acquires information of the vehicle external environment, and generates a travel route of the motor vehicle based on the estimated vehicle external environment; an auxiliary arithmetic unit that estimates the presence of the road and the obstacle based on the output from the vehicle external information acquisition device according to a predetermined rule without using deep learning, and generates a rule-based travel route in a free space on the road where no obstacle is present; and a safe route generation unit that generates a safe route, which is a travel route that the motor vehicle takes until the motor vehicle stops at a safe stop position that satisfies a preset criterion, based on the output from the vehicle external information acquisition device without using deep learning, the main arithmetic unit uses deep learning, the main arithmetic unit, the auxiliary arithmetic unit, and the safe route generation unit are independent from one another, and each independently execute arithmetic to generate the routes, and the automotive arithmetic system further includes an override processing unit, and based on a state of the vehicle received from a vehicle internal information acquisition device acquiring information about the state of the vehicle, the override processing unit prioritizes one of the travel route generated by the main arithmetic unit, the rule-based travel route generated by the auxiliary arithmetic unit, and determines a target motion of the motor vehicle so that the motor vehicle travels on the prioritized route, in a normal operation mode in which a failure of the vehicle has not been determined, and prioritizes the safe route generated by the safe route generation unit, and determines a target motion of the motor vehicle so that the motor vehicle travels on the safe route in a safe operation mode in which a failure of the vehicle has been determined. prioritizes one of the travel route generated by the main arithmetic unit, the rule-based travel route generated by the auxiliary arithmetic unit, and determines a target motion of the motor vehicle so that the motor vehicle travels on the prioritized route, in a normal operation mode in which a failure of the vehicle has not been determined, and prioritizes the safe route generated by the safe route generation unit, and determines a target motion of the motor vehicle so that the motor vehicle travels on the safe route in a safe operation mode in which a failure of the vehicle has been determined.