Suppose the one-way route is 325 km, the car averages 6.8 L/100 km, and fuel costs €1.72 per litre. The plan is to return on the same route, so the effective distance is 650 km before fuel is calculated.
State every input and unit
Distance is 325 kilometres, trip type is round trip, efficiency is 6.8 L/100 km, fuel price is €1.72 per litre, and the currency label is €. Selecting round trip doubles only the distance; efficiency and price remain unchanged.
Calculate the fuel volume
Multiply 650 km by 6.8 L/100 km and divide by 100. The result is 44.2 litres. This is an estimate based on average efficiency; mountain roads, congestion, roof boxes, temperature, and driving speed can move actual use above or below it.
Apply the price and read the rate
Multiply 44.2 litres by €1.72 to get €76.024, displayed as €76.02. Dividing that total by 650 km gives €0.1170 per kilometre after rounding. Tolls, parking, food, accommodation, and changing station prices remain outside this fuel-only estimate.