01
Distance and real fuel economy
Include the return journey and diversions. Use an average from several fill-ups or the trip computer rather than the best official figure.
If your car reports L/100 km, fuel needed is distance × consumption ÷ 100.
- Full distance
- Realistic average fuel economy
- Current fuel price
02
Cash spending or full cost
Fuel, tolls and parking describe the immediate money spent on the journey.
Tyres, servicing, insurance, tax and depreciation belong to ownership cost. Do not present marginal trip spending as the complete cost of running the car.
- Quick scenario: fuel and tolls
- Full scenario: add a per-kilometre cost
- State which scenario you use
03
Splitting the trip fairly
Equal division works when everyone travels the same route. If passengers join later or leave earlier, proportional shares may be fairer.
Agree beforehand whether the driver pays a share and how personal stops are treated.
Worked example
450 km, 17 km/L and fuel at €1.75/L
- Fuel needed
- 26.47 litres
- Fuel cost
- €46.32
- Tolls
- €32
Parking, wear and ownership costs are excluded from this cash-spending scenario.
Common mistakes to avoid
- Entering only the outward distance
- Using laboratory economy instead of real data
- Mixing km/L with L/100 km
- Calling fuel and tolls the full vehicle cost
Frequently asked questions
Which fuel price should I use?+
Use the expected station price or a current official average and update the input.
Should I include wear and tear?+
Yes for full economic cost; not necessarily for the cash needed during the trip.
How do I convert L/100 km to km/L?+
Divide 100 by L/100 km. For example, 6 L/100 km is about 16.67 km/L.
Sources and references
MIMIT · Official average fuel prices↗ACI · Vehicle running costs↗