With the regulator, you can adjust the size of the current that has flowed into the coil rotor. Not only that, but it also regulates the strength and weakness of the magnetic field in the coil rotor.
The stability that must be in the engine is strictly maintained by the car regulator. Even when the engine speed is not stable though. Fortunately, the condition of the engine speed fluctuates and still makes the car run well thanks to the presence of a regulator.