Electric, electronic and optical, measuring, signaling and checking devices and apparatus for operating and monitoring motor vehicles, namely, warning lights or electronic instruments that display an input signal in either a digital or analog form, for input signals relating to fuel or oil consumption, rotation speed, vehicle speed, temperature, fill-level, pressure, time, engine wear, overall distance traveled, and trip distance; odometers; motor vehicle speed regulating devices, namely, cruise controls for motor vehicles and vehicle speed limiters; fluid pressure and temperature regulators for vehicle fluids; electronic measuring devices for timing and recording driving time and stop periods; navigation apparatus for vehicles in the nature of on-board computers and freely downloadable software for use therewith; machine-readable data carriers featuring computer programs for use in vehicle on-board computers for recording measured values; electronic data recorders for recording measured values; replacement parts and drive parts for the aforesaid goods, in particular electrical switches, keyboards, blank data cassettes, computer monitors, optical, acoustic and writing signal generators, namely, generators of visual, audible, or written warnings, such as warning lights, alarm tones, or text-based warnings, and sensor systems comprised of temperature sensors, pressure sensors, speed sensors, fluid level sensors, engine wear sensors, or rotation speed sensors