Your 65th vehicle works 3 days a year.
It costs 42,000 to own and 1,950 to hire for exactly the days it is needed. Utilisation is usually presented as a list of idle assets. The useful version is a question about how many you should own at all.
Sized for the worst week of the year
Drag the line. Everything above it is a day you would be hiring; the gap below it is capacity you are paying for and not using.
- Vehicles owned
- 65
- Utilisation
- 66%
- Days you fall short
- 0
- Against sizing for peak
- —
Every day of the year, busiest first
peak 65 · median 42- Owning them
- 2,730,000
- Hiring the gap (0 days)
- 0
- Total for the year
- 2,730,000
Vehicle number 65 is needed 3 days a year. Owning it costs 42,000; hiring it for those days costs 1,950. It does not pay for itself — and everything above it is worse.
Peak demand is 65 vehicles and the median day needs 42. Owning for the peak puts utilisation at 66%; the cheapest fleet is 53 vehicles at 80%, which costs 388,950 a year less even after paying to hire on 61 days.
One number decides it
42,000 a year to own, 650 a day to hire. Divide one by the other and a vehicle needed fewer than 65 days a year is cheaper rented, every time.
The search for the cheapest fleet size lands in the same place without being told to, which is the reassuring part — two different methods agreeing on 53.
Utilisation targets get set as percentages, which is why they rarely change anything: nobody knows what to do with "we are at 66%". A count of days is actionable. It names a specific vehicle and tells you what to do with it.
| Vehicle | Days needed | Cost to own | Cost to hire | Verdict |
|---|---|---|---|---|
| #65 | 3 | 42,000 | 1,950 | Cheaper hired |
| #62 | 3 | 42,000 | 1,950 | Cheaper hired |
| #59 | 6 | 42,000 | 3,900 | Cheaper hired |
| #53 | 74 | 42,000 | 48,100 | Worth owning |
| #49 | 112 | 42,000 | 72,800 | Worth owning |
Vehicles are ranked by how many days of the year demand reaches them. The ones near the top of the fleet exist for a handful of weeks.
None of this works without the daily numbers
The curve above needs 365 honest daily counts of what was actually working. Almost no operation has those, which is why fleets are sized from memory and memory is anchored on the worst week anyone remembers.
- What counted as working
- Ignition and movement, not a booking sheet. A vehicle allocated to a job it never left the yard for is idle, and only telemetry knows that.
- Assets without ignition
- Trailers, gensets and plant report movement from the accelerometer, so they appear in this curve too.
- Days, not averages
- Utilisation as a monthly percentage hides the shape entirely. The whole argument lives in the distribution.
- A year of it, retained
- Sizing decisions want the full seasonal cycle. Six months of data will simply mislead you.
Why nobody actually runs at the optimum
The curve is arithmetic and the world is not. These are the reasons a sensible operator owns more than the model says, and they are good reasons.
- Hire availability is not guaranteed
- The model assumes you can hire on the day you need it. In practice your surge weeks are often the industry's surge weeks, and the rate is worse than the one above.
- Owned vehicles carry your livery and your standards
- A hired unit has no telematics, no inspection history and a driver who has not seen it before. That is a real cost the day rate does not include.
- Disposal is slower than a spreadsheet
- Coming down from peak means selling into whatever the used market is doing that quarter, and absorbing the finance settlement on anything still on a plan.
- This works better on some assets than others
- Trailers, gensets and light plant hire in easily. A specialist vehicle your customers recognise does not, and should be owned regardless of what the curve says.
The point is not to hit 53. It is to know that the gap between 53 and 65 costs 388,950 a year, and to decide deliberately how much of that you are buying as insurance rather than discovering it at renewal.
The other outcomes
Cut fuel and running cost
Idling, routing, fuel loss and overtime.
Reduce accidents
Coach the behaviour before it becomes a claim.
Stay compliant
Wasl registration and TGA reporting.
Stop theft and misuse
Geofences, after-hours movement, fuel siphoning.
Electrify the fleet
Which routes an EV can actually cover.