Another thought on this is that, there is no such thing as free lunch. If you take the fan off the drive shaft and replace it with an electric fan, the electric fan must be fed by the battery which must be recharged by an alternator. The alternator is a load to the engine.
Could this be so? It seems to me that the alternator is being spun by the belt all the time whether the car needs the current or not. It's not a so much a free lunch as it is just eating one of a number of lunches that might otherwise be thrown out and not eaten.
The alternator loads the engine the same amount whether the car uses the curent generated or not. It's not like the A/C compressor, which spins freely when not needed and engages the cluth and loads the engine an extra amount when it is needed.
Semibodacious Transmogrifications a Specialty
1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)
"Time flies like and arrow, yet fruit flies like a banana"