Electric, electronic and optical, weighing, measuring, signaling and checking apparatus and instruments for operating and monitoring motor vehicles, in particular consumption measurement devices, tachometers, speedometers, temperature meters, level metering devices, pressure gauges, time measuring devices and wear measuring devices, cruise controllers, pressure regulators and temperature controllers, monitoring devices for driving, duty and stop periods, tour, customer, trip and tailboard monitoring devices; on board computers, freely loadable with programs, in particular for locating and navigating purposes; machine-readable data carriers provided with programs (as far as included in this class), as well as measuring sensors, spare parts and drive components for the goods mentioned above, in particular switches, keyboards, sensors, data cassettes, monitors and optical, acoustic and recording transducers; software