Shell is test marketing a 94 octane fuel in our area. I use it but can't tell a difference. But since they sponsor Ferrari & Ferrari events I use thier gas. I agree you should use from busy stations. Jim Bob's Stop&Go may not sell much premium and its been there for monthes.
I have used Amoco white premium gasoline just because there is a station that is convenient nearby. If there was a Shell, I would use it. Most importantly, try not to use an older filling station. Their tanks have been in the ground too long, they probably have dirt, water, rust, whatever in those tanks, and as you know, water and gasoline do not mix well. I had to flush both tanks of my Boxer once as i discovered many pieces of rust that got in there somehow...had to be from where I was filling up.
If you are driving your F-car on a very regular basis, Shell may be the best bet; however if your car sees only occasional or weekend use, then Amoco Premium is better as its additives are known to store better and longer. It's also more compatible with "Stabil" and other storage compounds. In addition to the sage advice concerning old gas stations, etc. don't forget to avoid filling up while a supply tanker truck is on the premises. The high volume pumps on the truck really churn up the contents of the underground tanks and all kinds of nasty sediment can end up in your car.
I fill up with what ever premium gas is the least expensive. Most of the time I fill up my cars at Costco.
I use Sunoco Ultra 94... You can also use aviation fuel if you can get it. This is not the same as jet fuel which is essentially kerosene. Aviation fuel ranges from 110 to 120 octane and is blue in color. The other advantage to aviation fuel is that when it evaporates, it does not leave any residue behind like street gasoline. This is extremely important if you have an older Ferrari with carbs and do not use it frequently. I usually mix it 50/50 with Sunoco Ultra.
Shell 93 octane for the F-car, since they're an F1 sponsor. The rest of the vehicles get the cheap stuff...
Sunoco 94 has just vanished from CT and RI, and they only sell 93 as their highest octane grade now! I have never even seen a Chevron station despite the great talk about them, so I view that brand as virtual gas -- just like Sunoco 94 became in the northeast. So, I buy whatever high volume brand 93 I am near when I need it -- for my sports cars. The other cars/SUVs only get regular... Kind Regards, Chris