Guest: gasoline cost @20 miles per gallon driving from San Francisco, CA to Oklahoma City, OK. estimate fuel cost. 1,630 miles one way
Not sure what gasoline prices in the States are (I'm pretty sure dutch prices are far higher than those in the states), but you can calculate it in the following way;
Since 1630/20 gives the number of gallons you'd use the formula will be
Total fuel cost = (1630/20)*(Price of gasoline per gallon in the States)
edit: I just found that the average price of fuel in the states is 3.596 dollars per gallon.
This would give
Total fuel cost = (1630/20)*3.596 = $293.07
+2353 
