In the US an average compact car has a 1.6 L, 4 doors, auto trans, ac, air bags, ABS, and weighs about 3000 pounds. These cars are usually EPA fuel use rated around 25 city and 35 highway mpg. Since 100 km is about 62 miles, that means about two gallons of gasoline is about average. That's about 7.5 liters.