The answer to your question is "sort of". I looked high an low on the internet for specific information about Maverik, but it is a relatively small company and there is not much about them. However, I will tell you what I know, having some experience with the industry.
There are federal standards (Clean Air Act
) for gasoline sold in the US. The basic minimum is called "base fuel" and that is what gets piped out of all the refineries in the US to terminals (distribution centers) all over the country. Base fuel from one refinery is indistinguishable from base fuel from another. They usually send a low octane and a high octane base fuel.
The difference between gasoline brands comes from the additives used to keep engines clean. Additives are also required by the Clean Air Act. Off-brand gasolines, like you buy from grocery stores or Cosco, use the minimum standard "generic additive". Name brands use proprietary additives with fancy names like "Techron". These additives generally work better which is why they can get away with charging a few cents more per gallon.
At the terminal is where things really get interesting, though. Terminals are where the trucks that supply the gas stations come to fill up, and are owned by individual oil/gas companies. However, it is extremely inefficient to have a terminal for every single area where the company has a station. Think of the cost of building and maintaining a pipeline that's hundreds of miles long. What this means is that the gas companies contract with each other in places where they don't have their own distribution network. For instance, if ExxonMobil doesn't have a pipeline to Las Vegas, but Valero does, ExxonMobil will get its gas at the Valero terminal for its Exxon and Mobil stations. The terminal has different tanks containing each company's additive and when the truck driver swipes his ID, it mixes the appropriate additive with the base fuel as it goes into his truck. (Incidentally, medium octane is made at the terminal also by mixing low and high octane fuels.) A generic supplier of fuel can contract with Valero terminal and just request the cheap generic additive.
So if it's basically the same gasoline why is Maverik's cheaper? For one, they claim to be
an independent gasoline distributor. This means they refine and distribute using only their own refineries, pipelines, terminals, trucks, etc. I was unable to verify how true this is (some claim
they buy at least some of their gas from ConocoPhillips) but it would reduce some middle-man costs. Another reason is they are limited to a relatively small geographic area
and because of this can get their crude oil primarily from local sources (Utah, Wyoming, etc) and use local refineries. This reduces transportation costs, but wouldn't be possible for a larger operation because local supply isn't sufficient. Finally, I was unable to determine if Maverik uses the generic additive or its own. The generic additive might allow them to reduce costs a little.
I'm almost certain it isn't "thinning", unless you mean they add a higher percentage of ethanol. If they do, then yes, the gasoline will be less efficient (1-3%) and you have to buy more. The amount of ethanol, however, should be clearly marked at the pump. This would not be some underhanded trick, as many urban areas are required to add a certain amount of ethanol, and many consumers are demanding it, thinking it is a "cleaner" fuel (which I think is up for debate).
The best explanation is probably much more simple, and has to do with economics, and it's the main reason all the cheap brands are cheap. This guy's opinion article
sums it up pretty well, saying Maverik "uses their low gas prices as a marketing tool to get people to patronize their businesses and generate revenue through the sale of goods and merchandise. This stabilizes their profit margin, thus allowing them to sell gas a bit cheaper." Basically, they're selling fuel cheaper than they should be, banking on the fact that customers will buy into their "Adventure's First Stop" advertisements and buy lots of adventuresome beef jerky and sodas, which sell at a much better profit margin than gasoline.