How much petrol does a 2 liter engine use per km?

liter per km = liter for every 10km eg. 2lt every 10km so if you want to known how many lt per km divide by 10 and change the lt in to milliliters eg. 2(lt) x 1000 = 2000(ml) then 2000(ml) / 10 = 200ml and the answer is 200ml every km the working out here are base on traveling at a constant speed of 100kmph on a flat road.