Oil is almost exclusively traded in US dollars world wide before it enters other markets, so when the US dollar depreciates relative to say... the Saudi riyal, everyone everywhere on Earth pretty much feels the effect uniformly. Absent an exceptionally high tax or subsidy, the USD price of gas should be expected to be the same everywhere.
However, if the British Pound has appreciated in value relative to the American dollar, then saying the "converted price" is $7-8 per gallon doesn't give us any clear idea how expensive the British perceive gasoline prices to be.
kojax, not exactly; Regardless what currency is used to base a value, the final result to a currency is on it's value. That is if oil were traded in Euro's, the price for crude would have the same value as if it were traded in US$...
This morning (5/17/2010 8AM ET), a story in itself;
Commodity traded crude barrel; 70.55US$, 56.98 Euro and 48.72 Pd. converted.
Refined Crude to Lead Free Gasoline/Petrol gallon; 2.12 US$, 1.71 Euro and 1.46 Pd. converted.
Using the Gallon, these are the prices charged at the distribution point, on average and without regards to the various requirements placed on the refinery for individual State/Country demands, the basic price. Keep in mind, that currencies themselves are also traded, much as oil, but not necessarily setting the value of in State prices for goods or services, only those from out of State.
1 Gallon = 3.79 Liters, but for this purpose, lets talk in Gallons.
These prices are the product price in any Nation, converted to whatever that current currency value may be. Then in the UK, that gallon which cost American Retailers 2.12, cost the UK retailers the equivalent of 2.12US$ (1.46Pd). The reason the end price for that 2.12US$ being inflated to 7 or 8.00 is simply taxes, operating cost differences and whatever quality differences that may exist.