Authentication procedure for checking an operator's authorisation to enable a function of a motor vehicle, wherein a control circuit on the motor vehicle side initiates the following steps: - Contacting a Bluetooth Low Energy Interface, abbreviated: BLE interface, of the motor vehicle with an authorised device of the operator that is prepared for Bluetooth Low Energy Communication, abbreviated: BLE communication; - Transmission of authorisation data from the device to the BLE interface; - Evaluation of the authorisation data by means of stored reference authorisation data for the authorisation check of the device's authorisation; - Capturing of a biometric characteristic of the operator by means of a biometric sensor which is non-detachably arranged on the motor vehicle; - Biometrics check whether the captured biometric characteristic corresponds to stored reference biometric data of the authorised operator; - Enable the function by means of the control circuit after o the evaluation of the authorisation data has confirmed the authorisation of the device and o the biometric verification has shown that the biometric characteristic corresponds to the reference biometric data, wherein a Bluetooth connection is established between the BLE interface and the device after the biometric characteristic has been captured, wherein data derived from the biometric characteristic is used to generate a key, wherein the Bluetooth connection requires the evaluation of the key by the device, wherein the biometrics check and/or the evaluation of the authorisation data comprise the establishment of the connection. wherein a control circuit on the motor vehicle side initiates the following steps: - Contacting a Bluetooth Low Energy Interface, abbreviated: BLE interface, of the motor vehicle with an authorised device of the operator that is prepared for Bluetooth Low Energy Communication, abbreviated: BLE communication; - Transmission of authorisation data from the device to the BLE interface; - Evaluation of the authorisation data by means of stored reference authorisation data for the authorisation check of the device's authorisation; - Capturing of a biometric characteristic of the operator by means of a biometric sensor which is non-detachably arranged on the motor vehicle; - Biometrics check whether the captured biometric characteristic corresponds to stored reference biometric data of the authorised operator; - Enable the function by means of the control circuit after o the evaluation of the authorisation data has confirmed the authorisation of the device and o the biometric verification has shown that the biometric characteristic corresponds to the reference biometric data, - Contacting a Bluetooth Low Energy Interface, abbreviated: BLE interface, of the motor vehicle with an authorised device of the operator that is prepared for Bluetooth Low Energy Communication, abbreviated: BLE communication; - Transmission of authorisation data from the device to the BLE interface; - Evaluation of the authorisation data by means of stored reference authorisation data for the authorisation check of the device's authorisation; - Capturing of a biometric characteristic of the operator by means of a biometric sensor which is non-detachably arranged on the motor vehicle; - Biometrics check whether the captured biometric characteristic corresponds to stored reference biometric data of the authorised operator; - Enable the function by means of the control circuit after o the evaluation of the authorisation data has confirmed the authorisation of the device and o the biometric verification has shown that the biometric characteristic corresponds to the reference biometric data, o the evaluation of the authorisation data has confirmed the authorisation of the device and o the biometric verification has shown that the biometric characteristic corresponds to the reference biometric data, wherein a Bluetooth connection is established between the BLE interface and the device after the biometric characteristic has been captured, wherein data derived from the biometric characteristic is used to generate a key, wherein the Bluetooth connection requires the evaluation of the key by the device, wherein the biometrics check and/or the evaluation of the authorisation data comprise the establishment of the connection.