Why are petrol prices in Australia so high?

Because our goverment has no idea how to run the country properly.
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Australia has no petroleum reserves, they have to import most of it. The U.K. produces 5 times as much oil as Australia.
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I have to disagree with the above. Australia produces about 85% of the petrol it consumes. There are many other factors that affect pricing. Bottom line is that taxes account for a lot of the cost. And it's an expensive and dangerous process. And petrol companies don't mind making a tidy profit year on year either. (About 30% increase I hear, but can't find the stat) I found some good information from the Australian Competition and Consumer Commission which describes a lot of the factors involved.
References :
What Factors Determine Petrol Prices in Australia – (PDF)
http://www.accc.gov.au/content/item.phtml?itemId=706620&nodeId=8ca5449e025acc3840623d0997bf01a4&fn=Understanding%20petrol%20pricing_brochure%20–%20Oct2005.pdf

about the ACCC
http://www.accc.gov.au/content/index.phtml/itemId/3744