Question: how much diesel is required for 100 km?
Answer: A VW Rabit (diesel) in good tune on level paved roadway with a tail wind could at 80 kph make the 100Km trek on 4.5 liters. A full sized luxury sedan at high speed (150 kph) with uphill grade and a head wind would take 20–25 liters on that 100Km trek.