Well, fuel is fuel. In No. Va., we feed off a continental gasoline/petroleum pipeline out of Texas, via Louisiana. Traveling through the pipeline, they send 100K gallons of diesel, then 100K of unleaded gasoline, then, maybe heating fuel, then some quantity of JP for the airports that get shunted off to pipelines bound for Dulles International and Washington National, both of which have their own fuel dumps. Each product being separated by a plug that travels with the product called a pig. First few hundreds of gallons of each product change isn't so pure, they call it slops and store that for solvent production, and other stuff. Each run is made to order according to demand, and of course, there are stops all along the way between here and there that draw from the pipeline, too.
Point is, it's unleaded gasoline, generic. Here in this area of Northern Virginia we have two big dumps, one in Fairfax City, Va. owned by Star Enterprises (Texaco), and another out by I-95 in Springfield, Va. owned by a conglomerate that stores and mixes adds per spec the gasolines for Shell, Exxon/Mobil, BP, etc, etc. From there, tanker lines distribute to filling stations in No. Va., Washington DC, and D.C. metropolitan Md. stations. It's all underground, and it's ALL generic until it gets to the loading stand for each company's over the road tankers. Only diff is the additives.
So, a gas is top-tier, or it isn't. Do they spec what's in a top-tier fuel, and what's lacking in non-top tier? Or are these deep dark secrets?