There is this new electrical device called the Neo Socket Automotive Power Factor Corrector supposedly made by the Japanese company Miraizu that can be plugged into an automotive lighter's electrical socket which can increase the power factor of the AC electrical devices of a car. Power factor is the efficiency of AC electrical circuits which normally use components like inductors and capacitors that discharge and waste some of the energy delivered to them. And power factor correctors are devices that store up the wasted energy briefly in capacitors before sending the energy back to the electrical circuit. The theory of power factor correction is true and it can indeed increase the efficiency of AC electrical devices but does it really save the amount of fuel used by the internal combustion engine of a car? When the engine is running, the alternator is kept operating at a constant speed to generate a constant power output by a speed control differential gear which automatically lowers the gear on the shaft of the alternator as the engine speed increases so that the speed of the alternator remains constant. This means that even as the electricity wasted by the AC power components is saved, the alternator will still be running at the same speed to give the same power output and still use the same amount of power from the engine. So can using a power factor corrector really save the fuel used by an automobile engine? And is the car battery using an inverter to deliver AC power to the electrical components or can some of the car's electrical components use DC power as well? Because if the battery is connected to an inverter, then a power factor corrector can reduce the power consumption of the battery, allowing the battery to operate for longer periods of time without needing to be charged by the alternator, therefore the alternator can remain turned off for longer periods of time thus reducing the amount of fuel spent by the engine to run the alternator.