I only use Shell Premium. Get money off because I use
"T-Mobile Tuesday" app.
For past couple years, I was getting an extra 10 cents per gallon plus Shell's 5 cents off, (total of 15 cents off) but that changed about a month ago. Now with T-Mobile Tuesday app, for the past month, I've been getting an additional 25 cents off, plus Shell's 5 cents, for 30 cents off on Tuesdays. This past month, I've not only filled my cars, I've also filled all my emergency gas cans for my generator for when the power goes out next hurricane.
Although this has nothing to do with the above, for some reason, my car when cold, now starts immediately in the morning. In the past, it would take four to six seconds of cranking in the morning before the first start. Love it. (Perhaps Shell changed their Florida formula?)
As for mpg, around town is always different, depending on traffic, if I catch the lights, etc;
That being said, two weeks ago, I took my wife (cabin fever) for a ride up to Ocala, from my Mt. Dora home. Took back roads, through the Ocala National Forrest. Took my time. Told her we are taking a motorcycle ride using the car.
Got 40.0 mpg going there. Drove around Silver Springs, (using gas) then returned home on a different back road through the forest.
For the whole tide, got 38.x mpg.
Don't know if it was because I took my time or because Shell Premium has a different summer formula.
As I've said before, I use (Shell) Premium for the cleaners, not the octane. If on a trip, and not a Tuesday, I'll sometimes use Chevron or Mobil Premium. Never "Generic" gas.