After much research, the following information has been determined.
First, a brief explanation of your car’s electrical system is in order.
The battery in your car does very little aside from activate the starter. It is the alternator that actually powers the car while it is running. The battery is still in the loop so that, should the car need MORE than the alternator is producing it can feed from the battery. You can actually start your car, and then remove the battery, and your car, unless it has bad electrical problems, will continue to run with all your electrical components functioning properly (I have actually done this on numerous occasions for various reasons).
The alternator produces or, more correctly, induces electricity by converting some of the mechanical energy produced by your engine due to the combustion of gasoline. The harder your engine has to work, the more gasoline it consumes.
As the various electrical components in your car require electricity or, more correctly, as the resistance is increased the voltage will decrease. The voltage regulator in your car will see this, and tell your alternator to increase power which it does by increasing the current in the electromagnets on the rotor of the alternator which increases the magnetic field, which therefore causes increased induction in the coils of the stator and therefore increases the current output. When your alternator begins generating more current, the voltage levels will return back to normal.
The exact opposite occurs when your car’s electrical system experiences a decrease in resistance.
So, the remaining question is this: Does it require additional engine power to turn the rotor of an alternator when the strength of the magnetic field produced on the rotor increases?
My initial thoughts would be yes. The reason I say this is simply because I know that when two magnets are strong it is more difficult to get them close together (or apart, depending on whether they are repelling or attracting one another) than when they are weak.
Unfortunately, I can’t find a website that outlines this precisely. If any of you can, I would appreciate it.