International Gasoline Prices
The prices shown are expressed in US dollars and US gallons. These quarterly figures represent averages for the least expensive gasoline available at name-brand retail service stations.
US - $1.43
Hong Kong - $5.24
London, England - $4.83
Oslo, Norway - $4.38
Tokyo, Japan - $4.34
Quito, Ecuador - $.50
Jakarta, Indonesia - $.52
Kuwait City, Kuwait - $.76
Riyadh, Saudi Arabia - $.93
Source: Runzheimer International, Rochester, Wisconsin.
I got this from http://www.galtglobalreview.com/world/world_gasoline.html
I'm not entirely sure how accurate it is though, since the figure quoted for the US seems to be much lower than the amounts posted by other posters living in the US. I'm also not sure at what time the data was collected. However it appears to be a good enough guide on comparing costs between the selected nations.
For the record the cheapest petrol available in Brisbane today is AUD$1.02 a litre, which would be USD$2.86 per gallon on this table using today's exchange rate.