In-vehicle computer system and autonomous driving assistance system

Provided is a technology capable of adding a new function by updating a program of an in-vehicle computer system. An in-vehicle computer system includes a plurality of ECUs. Each ECU is able to communicate with at least one other ECU via a communication bus. An in-vehicle computer system includes a measurement means that measures an ECU state for the ECUs, an estimation means that estimates a vehicle state based on the ECU state and a connection configuration of a communication bus, and a management means that acquires an update program and execution conditions of the update program. The management means selects a first ECU that is to execute the update program based on the vehicle state and the execution conditions. The first ECU executes the update program. The management means determines whether or not an output delay constraint of the update program is satisfied. The management means terminates execution of a redundancy program redundant to the update program.