Here is a small calculator for those who are too lazy to count. You should enter distance traveled, in kilometers, tank capacity, average fuel consumption per hundred kilometers (each car already seems to have that) and the price per liter of fuel. It calculates - fuel consumption in liters, fuel tanks, and money. It's obvious that the calculation is quite trivial and that all the calculated values are based on the average consumption per one hundred kilometers.
Distance in miles or kilometers
Tank capacity in litres or gallons
Average fuel consumption per 100 (miles or kilo meters)
Fuel price per one litre or gallon (same fuel unit must be used as in previous inputs)