What does your car cost per kilometre?

Which costs should you include?

Fuel or charging and maintenance are familiar costs. A fuller picture also includes fixed costs such as insurance and road tax, plus depreciation.

Use the same period for costs and distance. A figure excluding depreciation is not directly comparable with one that includes loss of value.

€500 in costs, 2,000 km driven

In an illustrative month, you record €350 for fuel and €150 for maintenance, and drive 2,000 km. Recorded costs are €500 ÷ 2,000 = €0.25 per km. This example excludes insurance, road tax and depreciation.

Keep track of what is included, so you can compare your own figures consistently across periods.

Calculating trip and ownership costs over one period

Decide which question you want the figure to answer. For one extra trip, the extra costs matter. For ownership, fixed expenses and depreciation matter too. Both calculations can be correct and produce different answers.

Choose a period with records of both spending and distance. Use matching start and end dates and state whether you included depreciation, insurance, taxes and maintenance.

Use the period in which you owned the car. If you bought it halfway through the year, start with the odometer reading at handover. Record whether annual charges were prorated or whether you counted only bills actually paid during the period you are comparing.

Comparing fixed and variable costs

You drive 12,000 kilometres in a year and include 4,800 euros of spending. That is 40 cents per kilometre. If you count only 1,200 euros for fuel in the same period, the result is 10 cents per kilometre. The difference comes from the choice of costs.

An expensive repair can dominate one month. A longer period adds context. When comparing two cars, use the same expense categories and the same way of allocating them.

When comparing cars before buying, run two scenarios with different annual distances. Keep insurance and other fixed items visible in both scenarios. That shows how much of the difference comes from spreading expenses over more kilometres. Mark estimated items separately. Later you can replace them with actual payments without rebuilding the calculation. In a partial year, for example, flag large maintenance invoices so the comparison shows the effect of a one-off bill. Keep receipts and odometer readings for the same time span.

You can also calculate a second figure using only fuel or electricity and other costs tied directly to driving. Label it separately so you remember which question it answers.

Keeping expenses and odometer readings

Keep the odometer readings and category breakdown. For depreciation, record the purchase and residual values that you assumed.

A repair in December can dominate a monthly graph. Keep a breakdown by category alongside the average. When comparing the car with the following year, you can see whether fuel, fewer kilometres or a single invoice accounts for most of the difference.

When ownership changes midway through a month, use the odometer reading on the handover date to separate the distance driven before and after you owned the car.