Estimating the true cost of a truck goes beyond its purchase price. Between fuel, maintenance, tolls, insurance, and depreciation, the actual amount spent over the vehicle’s lifespan far exceeds the figure on the initial invoice. To manage the profitability of a fleet or simply compare two acquisition options, it is necessary to model all these items and relate them to a common unit: the cost per kilometer.
Cost per kilometer of a truck: fixed costs versus variable costs
The distinction between fixed costs and variable costs is crucial for any reliable estimate. A fixed cost remains stable regardless of the mileage driven. A variable cost changes directly with the vehicle’s activity.
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| Cost Type | Examples | Behavior |
|---|---|---|
| Fixed | Depreciation, insurance, axle tax, financial charges | Identical whether the truck is driving or remains at the depot |
| Variable | Fuel, tires, tolls, routine maintenance | Increases proportionally with mileage |
| Semi-variable | Major repairs, technical inspections | Related to wear and the vehicle’s age |
Bringing each item to a cost per kilometer allows for the comparison of trucks with different usage. A vehicle that covers a high annual mileage dilutes its fixed costs over more kilometers, which mechanically lowers its unit cost. Conversely, its variable costs (fuel consumption, tire wear) weigh more heavily in absolute value.
The calculation of the true cost of a truck gains accuracy when isolating these two categories of expenses before adding them together.
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Depreciation and residual value: the item many underestimate
The purchase price grabs attention, but it is depreciation that determines the true cost of ownership. A truck loses a significant portion of its value within the first few years. The difference between the acquisition price and the resale value at the end of its fleet life constitutes the true cost of capital immobilization.
Several factors influence this loss of value:
- The total mileage displayed on the odometer, which remains the primary criterion for depreciation in the used heavy truck market
- The general mechanical condition, documented by a complete maintenance history (invoices, workshop visits, major parts replacements)
- The engine type, as a diesel truck and an electric truck do not depreciate at the same rate, with the latter having a residual value that is still difficult to anticipate in the current market
- The brand and model, as some manufacturers retain a better rating at equivalent mileage
Ignoring depreciation amounts to underestimating the cost of ownership by several hundred euros per month. Fleet management companies systematically incorporate this projection into their total cost of ownership (TCO) calculation tools.
Diesel, CNG, or electric engines: different cost structures
The comparison between engines is not limited to the price of fuel or kWh. The hierarchy of expense items changes depending on the chosen engine type.
In a diesel truck, fuel represents the dominant variable cost. Mechanical maintenance (oil changes, filters, injection system) incurs regular but predictable costs. The resale value remains relatively clear due to a mature used market.
In an electric truck, the energy cost decreases significantly per kilometer. Routine maintenance also decreases (no engine oil changes, fewer wear parts). However, depreciation and the initial acquisition cost are significantly higher. The residual value remains uncertain, due to insufficient historical data in the resale market.
CNG (compressed natural gas) sits between the two. The energy cost heavily depends on gas prices, which can be more volatile than diesel during certain periods. Maintenance is similar to that of a conventional diesel.
To compare these three options, it is necessary to model each scenario over an identical duration (at least five years) and a realistic projected mileage. The cost per kilometer over five years is the only indicator that allows for a reliable comparison between engine types.
Cost simulator and CNR trinomial formula: reference tools for road transport
The National Road Committee (CNR) publishes a simulator that breaks down the cost price of a heavy truck according to a trinomial formula. This formula separates three components:
- A mileage term (fuel, tires, maintenance), proportional to the distance traveled
- A time term (depreciation, financial charges, insurance), proportional to the time of use
- A daily term (personnel costs, driver’s social charges), related to active days
This breakdown allows for precise isolation of the impact of a parameter change. For example, an increase in fuel prices only affects the mileage term. An increase in loading wait times impacts the time term.
The CNR trinomial formula remains the reference tool in France for carriers who wish to verify the consistency of their rates. It also serves as a negotiation basis between shippers and carriers during contract revisions.
Other online simulators offer a simplified approach focused on cost per kilometer. They are sufficient for a first estimate but often lack granularity on structural charges and indirect costs (downtime, administrative management).
Hidden costs of a truck: downtime and indirect charges
Breakdowns and unplanned immobilization generate an opportunity cost rarely quantified in standard estimates. A truck at a standstill is a vehicle that does not generate revenue while continuing to incur fixed costs.
Unplanned downtime can represent a cost greater than the repair itself. Loss of contracts, late penalties, reorganization of routes: these consequences remain invisible in a standard cost table.
Administrative charges related to vehicle management (regulatory follow-up, management of fines, mileage reporting) also add up. They weigh little individually, but when accumulated across an entire fleet, they form a significant item.
A rigorous tracking of maintenance history and a preventive maintenance plan reduce the frequency of unexpected immobilizations. Anticipating the replacement of wear parts is cheaper than suffering a breakdown during operation.