How to Calculate the Fuel Cost of a Trip

Works out the fuel a trip needs from the distance and the fuel efficiency, then multiplies by the price. Tolls are added for a total, and the total is split between the people travelling.

This works out the fuel a trip needs from the distance and the efficiency, then multiplies by the price per litre.

fuel (L)=distance (km)efficiency (km/L),cost=fuel×price\text{fuel (L)} = \dfrac{\text{distance (km)}}{\text{efficiency (km/L)}}, \quad \text{cost} = \text{fuel} \times \text{price}

Tolls are added for a total, and the total is divided between the people travelling.

Example

Driving 400 km in a car managing 15 km/L needs 400÷15=26.7400 \div 15 = 26.7 litres, which at 175 a litre costs 4,667, or 11.7 per kilometre. Adding 5,000 of tolls brings the total to 9,667, which is 4,833 each between two people.

Efficiency tells

The same 400 km in a car managing 10 km/L takes 40 litres and costs 7,000. At 20 km/L it takes 20 litres and costs 3,500. Twice the efficiency is half the bill, and over 10,000 km a year that gap runs past 80,000.

Real efficiency falls short of the figures quoted

Actual consumption typically runs 10 to 30% worse than the official rating. Traffic, air conditioning, a loaded car and hills all take their toll. Working out your own figure from the distance covered between two fill-ups gives a far more realistic estimate.

Notes

Only fuel and tolls are counted here. Parking, depreciation, insurance and tax are not.