This is very interesting. In The Real Economics of Oil, Sheldon Drobny sats that gasoline is really only a waste product from the refining process. The real profit is from products like asphalt, lubricating oils, paraffin wax, heating oil, tar and others.
Essentially, gasoline is a waste product of the oil refining process and the oil companies get rid of their hazardous waste and charge the public to do that. It actually reduces the cost of the oil refining process and at the same time contributes greatly to the greenhouse effect of global warming.
Go have a read.