[oil pan 4]

I am not asking, I already know.
Many have pondered, some have argued.

I finely got around to measuring how much power it takes to turn a P/S pump. ( about this time last year)
It looks like if you can keep the P/S turning at 850rpms it takes hardly any power to turn, around 150 to 200 watts.
But when you bring it up to a more normal cruse speed say about 2,000 rpms power draw goes up quite a bit. It took a little over 500 watts to keep it turning at that speed.
That is with the pump just spinning with out any input to the steering wheel.
For my suburban 500w gets about half MPG.
That should scale down to about a 2 to 3mpg savings on a small car. Assuming my suburban takes about 35 to 40 horsepower to maintain 60mph and a small car takes about 10 horses to go the same speed, then account for the car engine turning the pump about 3000rpm.

Beyond 2000 RPMs I believe that you will see a proportional increase, wattage doubling as the RPMs double.