Gas prices are ramping up again as a potential military action against Iran puts uncertainty into the oil market. This volatility is going to be exploited for all it's worth by speculators. There is only one way to fight back and try to stick it to the speculators and here it is.
Oil speculation works on the premise that people will buy oil until the price really starts to hurt them, en masse. When it really starts to hurt they pull back and find ways to conserve. This pull back creates an oil surplus in the system that must be cleared by price reductions. The oil system, from well to gas tank, doesn't have a lot of slack built into it in that way. It cannot sustain a surplus of oil that is too large because it is not designed for it.
We can leverage this lack of surplus capacity in the oil supply chain to hurt the speculators who try to take advantage of the market.
How do we do this?
There are two key elements: use less gas, and keep less gas in your car.
How can I use less gas?
1. Inflate your tires to their proper level.
2. Combine trips.
3. Learn about hypermiling practices - http://www.hypermiling.com/
4. If you have multiple cars, choose your most efficient vehicle whenever feasible.
Keep less gas in your car.
There are about 135 million registered vehicles in the USA. If each one has an average fuel tank of 12 gallons and that tank is on average half full then the fuel stored in vehicles is 810 million gallons, at any given time. If you compute a barrel of oil as 25 gallons of gasoline there are 32 million barrels of oil sitting in the fuel tanks of the cars.
If instead of filling up a full tank at the gas station we only did half a tank, and following the same assumptions as above, (12 gallon tank, half full on average) then if every vehicle was run the same way we'd only have 16 million barrels equivalent of oil sitting in the gas tanks of nation's cars. 16 milion barrels is almost a day's supply of oil. This is a lot. The market would have an oil glut to deal with because the supply that is usually siting in car gas tanks would have to sit somewhere else. It would cause a backup that would have to be cleared with a price reduction (which would hopefully burn the speculators).
Conclusion
To fight oil speculation, reduce your driving, maximize the efficiency of your vehicle with good maintenance, learn how to drive as efficiently as possible and as a last measure don't fill up all the way. Finally, this only works if it's adopted en masse. It would need to be an organized effort to have any chance at being effective.