Cost
How to Identify Your Most Expensive Vehicles
A practical method for finding which vehicles in your fleet are costing disproportionately more than others — and the warning signs worth watching for before the cost becomes obvious.
How do you identify your most expensive fleet vehicles?
Identifying your most expensive vehicles requires comparing cost per kilometre — not total spend — across vehicles doing similar work, since a vehicle covering more distance will naturally cost more in total without necessarily costing more per kilometre.
Why total spend is a misleading starting point
Ranking vehicles by total monthly cost mostly just ranks them by how much they were used. A vehicle that covered 4,000 km will usually cost more in total than one that covered 1,500 km, even if the second vehicle is, per kilometre, considerably more expensive to run. Total spend answers “where did the money go” without answering the more useful question: “which vehicle is inefficient relative to its own workload.”
A four-step method
1. Calculate cost per kilometre for every vehicle, using total running cost (fuel, maintenance, repairs, tyres — see what a vehicle really costs per kilometre) divided by distance travelled over the same period.
2. Group vehicles by type and use case. Compare bakkies against bakkies doing similar work, not against trucks or against bakkies on a completely different route profile. A fair comparison only works within a like-for-like group.
3. Look for outliers within each group, not just the highest absolute figure. A vehicle costing 25–30% more per kilometre than others in its group is a genuine outlier worth investigating, even if it’s not the single highest-cost vehicle in the fleet.
4. Check the trend, not just the current month. A vehicle that’s been creeping upward for three or four consecutive months is a different situation from one with a single expensive month caused by an isolated repair.
What usually explains an outlier, once you find one
- Driver behaviour — harsh acceleration, braking or speeding driving up fuel and wear costs on that specific vehicle.
- Deferred maintenance — a vehicle that’s had services pushed back, now costing more in repairs than it would have in scheduled servicing.
- A recurring mechanical issue — a fault that’s been repaired repeatedly rather than properly diagnosed and resolved.
- Age and mileage — an older vehicle simply approaching the point where its running cost justifies replacement.
- Genuine differences in use — sometimes the “outlier” is explained by legitimately harder conditions (terrain, load), in which case it isn’t really an anomaly, just a different baseline.
Why this is worth doing monthly, not annually
Waiting until year-end to review vehicle costs means an expensive vehicle has usually been expensive for most of the year before anyone notices. Reviewing cost per vehicle monthly catches the trend while it’s still a small gap, when the underlying cause — a driver habit, a deferred service — is easier and cheaper to address than after months of accumulated cost.
This kind of ongoing comparison is the core of fleet cost analysis as an active service, rather than a once-a-year spreadsheet exercise.