In a quite detailed account, one Tundra owner finds out, yes:
Tundra Fuel Economy: Fitch Fuel Catalyst Findings
Its theory is sound, unlike the Tornado or fuel line magnets, that the quality of gas is not equal between one station to another. Many conditions exist, from the age and quality of the underground tanks, to the last time the station's employees changed the filters on the pumps. Typically there are two permanent filters and one disposable filter on a gas pump, a steel mesh screen that catchs 100 micron and larger deposits, a plastic/nylon mesh screen that catches 70 micron and larger deposits and then a disposable filter, to which there are many options available to station owners from as tight as 4 micron (Which would require changing daily) or as loose as 10 micron (Which they could use for a few days), and these filters do not feature bypass valves. If you get a pump that is pumping quite slowly, it has nothing to do with the time of day, the temperature outside or how many other people are at the pumps, its simple mechanics, that fuel is trying to be shoved through a clogged filter.
When considering the quality of your station's restroom, the staff's appearance and attitude, you have to ask yourself if the gas you are paying near $3/gallon for is actually worth it.
So back to the Fitch.. for the return on investment, it will take some time, but you can do what the Fitch does, by carefully shopping for gas. The best bet is to fill up at Quik Trip, it is the only gas station I know of that is company owned, operated and maintained, and not a franchise. On top of that QT also qualifies as a Top Tier gas distributor, a standard set by BMW, Mercedes-Benz, Audi, Ford and GM, for the highest quality of gas (Before it is delivered to the stations, however).