Diagnostic apparatus of electronic regulating apparatus for land vehicles, namely, a vehicle communication interface for identifying fuel injection and anti-locking brake failures; computer software for diagnostic apparatus of electronic regulating apparatus for land vehicles for collecting and analyzing data collected by the electronic regulating apparatus, identifying electronic failures, and controlling the electronic regulating apparatus; computer software for diagnostic apparatus of electronic regulating apparatus for land vehicles for testing fuel injection and anti-locking braking systems and identifying failures; computer software for testing apparatus for remote diagnostic systems for land vehicles; measuring and testing machines and instruments for land vehicles, namely, telecommunication line integrity testing instruments, gas testing instruments and automobile control sensor testing instruments; measuring and testing machines, namely, electric and magnetic meters and instruments for testing the performance of land vehicles, namely, gas meters, flow meters, circuit testers, speedometer testers, energy meters for tracking and monitoring energy usage, vibration and frequency meters, fuel pump, brake fluid, antifreeze, battery, voltage and diesel injector testers, speedometers, tachometers, temperature meters, oil pressure meters, voltmeter ammeters; electronic machines, apparatus and their parts, namely, VCIs (vehicle communication interfaces), data logger; electronic control unit for engines for land vehicles for monitoring engine performance and delivering re-caluclated sensor values to the original engine control unit to change engine performance; electronic control system units for vehicle engines; electric and magnetic meters and testers, namely, voltage testers; speedometers, tachometers, temperature meters not for medical use, oil pressure meters, voltmeter ammeters, instrument clusters comprising meters indicating vehicle and engine conditions, combination pressure, temperature and speed engine rotational speed, fuel and voltage meters, odometers, air flow meters for engines and output signal level, signal timing, voltage and amperage testers for engine or automobile control computer