US gallon is different than normal gallon I believe. Even with that factored in it is much cheaper over here for fuel. I saw fuel today for $3.57 here. I only have a 17 gallon tank and normally only fill up 15 gallons at a time for roughly $50-55.
My parents have much bigger tanks though with diesel, and at current prices it is $160USD, would hate to see what it is in Europe for the same amount.