text: if oil is a commodity, why are gas prices per gallon so different around the world? for example, why does gas cost $0.16 a gallon in brazil, $3.00 a gallon in the u.s. and $5 a gallon in europe? the single largest factor which effects gas prices is the cost of refining.  if you notice the countries with the highest gas prices, none of them have the capability to refine.  even back when gas was .30, .40, .50 cent a gallon in the us it was $2-$3 a gallon in europe.  in brazil, petrobas is their source of gas and it is state owned company.  gas sells for over $3.50 us a gallon.  you must be referring to natural gas used for heating which sells for less but i can't imagine $0.16 a gallon is acorrect figure even for natural gas.