According to Wiki, The US has about 240 million of the world's 600 million cars.
That makes the US the largest consumer, and there are price advantages of buying bulk. There is also the greatest opportunity for speculator profit.
As for US cars getting 10MPG. Last year's price hike, changed car buying habits, which is why the car industry and the economy tanked so badly. Low gas mileage cars went out of favor, which is where the highest profit margins were in the new car sales. You think the speculators didn't notice? You think some of them didn't make a fortune on oil speculation? You think there is any incentive to try and manipulate the market for repeating that scenario of making a large profit? Do you think the the oil companies mind their product being the focus of a money making scheme?
The world population of cars is changing, though.
http://www.rqriley.com/images-spech/slide-2.jpgAs foreign car ownership per capita increases, the US buying power advantage will diminish, and the gas prices to run those autos will increase as it becomes less attractive for commodity speculators.
In the mean time, North Americans are driving again and using more gas. You can expect the price to again rise to record levels until the market finds the same pain threshold that was hit last year. Once again, Americans will either stop buying gas, or because they need gas to earn an income, stop buying other things so they can pay for gas. The economy will again tank or at least soften, and the price of gas will drop, as speculators sponge out the money from the economy (no worries, the government will just let banks print more money). Afterwards the people will acclimate to the price change and repeat the economic cycle, returning to higher gas usage, which the speculators will capitalize upon.
What is your personal gas price pain threshold? At what price do you stop buying gas? I'll bet it is higher than you think. And, the speculators are betting on that, too.