We've all become a lot more interested in the secret science of what determines gas prices. The Cincinnati Enquirer just painstakingly analyzed price data from 716 gas stations in May and June using the Oil Price Information Service. Their most peculiar and potentially useful finding was that gas is cheapest on Tuesdays.

Over the whole period among all those stations, gas was an average three cents a gallon cheaper on Tuesdays than Wednesdays, and once it jumped 16 cents overnight. The Enquirer found that Wednesday was the day stations raised prices for the upcoming weekend, and that they lowered it just after the weekend.

The Enquirer says gas mavens have known this all along, though it was certainly news to me. If gas stations are expecting to even out their demand with pricing, will it work if people don't understand the weekly cycle? The story says: "Experts say gas always has been cheapest midweek, when demand is lowest. But the exact cheapest day is likely to change at any moment, without notice...." So, if we all start buying on Tuesdays, the cheapest day will move.

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Wal-Mart (NYSE: WMT) instituted a new customer slogan this year: "Save Money. Live Better." Although it was intended to reinforce the retailer's position that it helps families in an age of increasing prices and general inflationary pressure, much of the public didn't get the memo, apparently.

Keep in mind that it's hard to completely trust anything by either the retailer or its watchdog groups like Wal-Mart Watch, the latter released a survey that concluded only 4% of people believe that Wal-Mart saves the average American family $2,500 annually. The same report says that customers may indeed be paying less, but Wal-Mart is not the only company that can help them pad those wallets and fill those purses.

Of course, Wal-Mart Watch says that the study that backs Wal-Mart's "$2,500" claim credits just the retailer's existence with saving the customer that much. Perhaps that's through pricing competition in the area and inflation control more than Wal-Mart customers specifically saving that much by shopping at Wal-Mart? That could certainly be inferred here.

Regardless, does the mere existence of Wal-Mart control the complete, surrounding retail ecosystem, causing prices to remain ultra-competitive? Probably so -- and Wal-Mart's "Save Money. Live Better" might just be a statement of fact rather than a corporate pitch. Either way, there's probably some good truth in there.