Reading the owners manual and what Ford published about our cars, the H.P. and torque numbers have a note underneath that day they were obtained with 93 octane.
The car can run on 87. It looks at the knock sensors and other inputs and adjusts timing to not hurt itself. There is a PID called OCT-ADJ that gives an indication of what quality/octane the fuel is. 1 would be bad, 100 would be the best.
If you run good 93 the car will give everthing it can within its programming. If you run 87, it will run, but not to it's full potential.
What I cant tell you is if there is any benefit to 90, 91, 92, 93 as the kicker is the pump always says MINIMUM octane average. So that 87 may be 87 becuase there is more volume sold. That 89 or 90 may have a higher octane so that as it degrades it doesnt fall below the advertised octane. However, I cant be sure because I have no way of testing octane myself.
I've run BP 90+ in my car since I bought it new. Ive recently started running Sam's Club 93(?) Becuase its .5 cheaper. My OCT ADJ always have 100.
I've been meaning to put a tank of 87 in and whatcha pids to see the difference, but out of habit I keep hitting that 93 button.