I run mid grade nearly all the time in my car and only run premium once every 3 fill ups if I remember.
Unless you are running the car hard or loading (high load, low RPM) its not gonna matter IMO.
YMMV
BTW this is coming from a guy that was fanatical about buying only Shell v-power and running only the finest PAO oils. All that additional expense added up to NOT, NADDA not a damn thing except less $$$ in my pocket.