A while ago, a thread was discussing mid-grade fuel and someone mentioned that virtually all stations blend mid-grade at the pump by mixing regular and high octane gas.
FWIW, a "High's" gas station opened in my area that sells Carroll brand fuel. Upon speaking to the manager (who happened to be outside while tanker deliveries were being made), I was informed they have separate tanks for mid-grade and it's delivered to them as such (i.e. not mixed by the driver when filling the tank).
Just passing along first-hand information because statements in that previous thread implied that all modern stations mix at the pump. This station is brand new, built from the ground-up and six months ago, was an empty lot. Suffice it say, don't count on mid-grade being fresh gas unless you have specific knowledge about the station.
Ray