Method for operating a computer system for a motor vehicle, wherein the computer system comprises a vehicle computer apparatus fixedly installed in the motor vehicle, a detection apparatus (16, 17), an evaluation unit, and a data storage apparatus (20, 21) not fixedly installed in the motor vehicle, wherein the data storage apparatus (20, 21) is designed to transmit to and/or receive from the vehicle computer apparatus operating system installation data operable as a virtual machine, VM, via a communication link with the vehicle computer apparatus, comprising the following steps: - determining, by means of the evaluation unit, a motor vehicle-related activation event for operation of operating system installation data stored on the data storage apparatus (20, 21) as a virtual machine on the vehicle computer apparatus on the basis of activation indicator data detected by means of the detection apparatus (16, 17); - as soon as the motor vehicle-related activation event has been determined, receiving the operating system installation data stored on the data storage apparatus (20, 21) and starting the operation of the virtual machine by means of the vehicle computer apparatus; - determining, by means of the evaluation unit, a motor vehicle-related deactivation event for the operation of the virtual machine on the vehicle computer apparatus on the basis of deactivation indicator data detected by means of the detection apparatus (16, 17); and, - as soon as the motor vehicle-related deactivation event has been determined, transmission of operating system installation data describing a current operating system state of the virtual machine to the data storage apparatus (20, 21) and a storage device of the vehicle computer apparatus by means of the vehicle computer apparatus, wherein the data stored in the storage device of the vehicle computer apparatus are automatically deleted if the data have not been accessed for a predefined period of time and/or if storage space in the storage device falls below a predefined minimum storage space value, and wherein, upon a subsequent activation event, it is first checked whether new operating system installation data have to be transferred at all from the data storage apparatus (20, 21) or whether all or at least some of the required operating system installation data can be loaded from the storage device. - determining, by means of the evaluation unit, a motor vehicle-related activation event for operation of operating system installation data stored on the data storage apparatus (20, 21) as a virtual machine on the vehicle computer apparatus on the basis of activation indicator data detected by means of the detection apparatus (16, 17); - as soon as the motor vehicle-related activation event has been determined, receiving the operating system installation data stored on the data storage apparatus (20, 21) and starting the operation of the virtual machine by means of the vehicle computer apparatus; - determining, by means of the evaluation unit, a motor vehicle-related deactivation event for the operation of the virtual machine on the vehicle computer apparatus on the basis of deactivation indicator data detected by means of the detection apparatus (16, 17); and, - as soon as the motor vehicle-related deactivation event has been determined, transmission of operating system installation data describing a current operating system state of the virtual machine to the data storage apparatus (20, 21) and a storage device of the vehicle computer apparatus by means of the vehicle computer apparatus, wherein the data stored in the storage device of the vehicle computer apparatus are automatically deleted if the data have not been accessed for a predefined period of time and/or if storage space in the storage device falls below a predefined minimum storage space value, and wherein, upon a subsequent activation event, it is first checked whether new operating system installation data have to be transferred at all from the data storage apparatus (20, 21) or whether all or at least some of the required operating system installation data can be loaded from the storage device.