Let's put our thinking caps on for a moment gentlemen. Ask yourself how a COMMODITY jumps that amount in a couple of days.
1. Pure greed; i. e. station operator pushing price up or the jobber who supplies him. If this is the case, and a person could prove it, you could reap a nice little "reward" thru consumer protection laws. This would be hard to "prove" but a bulldog attorney would suck it up if they thought they could prove it.
2. Big Oil Manipulation... . see above.
3. The Commodity Markets; AAAAhhhhh yes, the good old free market. Here my friends is where the RISE in prices of COMMODITIES (of which diesel is one) takes form. From the comfort of your home, in your underwear, you to can buy Diesel Fuel, pre tax. Only thing is, to follow thru with the purchase you must have storage for roughly 55,000 gallons of diesel fuel.
Don't think for a moment that ANY and EVERY large scale diesel user didn't buy diesel for possibly the next six months at the recent lowered prices. This in turn caused a spike in prices when the market sees less avaliable. Since the dot com bubble, folks who "day traded" are now looking at commodities to play every day.
If you still think my view is wrong, do some investigation on commodity markets the last three years.
Jim