Vehicle Replacement Calculator
An old vehicle feels cheap because it is paid for. That feeling is where replacement decisions go wrong. This calculator sets what the vehicle will cost you over the next twelve months against what its replacement would cost per year, and reports the difference.
Your numbers
A trade or auction figure you would actually accept this month.
The gap between these two fields is next year's depreciation.
Include the jobs you know are coming: the clutch, the injectors, the test.
Use this vehicle's real consumption, which is worse than it used to be.
Workshop time plus the days it waits for a part.
What the vehicle would have contributed. Enter 0 to ignore downtime.
What you expect to get for it at the end of its holding period.
Averaged across the holding period, not the first year under warranty.
Same annual distance as the old vehicle, at the newer consumption.
Result
Annual saving from replacing now
3,933
Positive: the replacement costs less per year than keeping this vehicle.
- Maintenance break-even
- 2,867
- Cost of keeping (next 12 months)
- 29,600
- Cost of replacing (per year)
- 25,667
- Depreciation if kept
- 4,000
- Depreciation if replaced
- 8,667
- Downtime if kept
- 3,200
The formula
- Depreciation if kept = Value today − Value in twelve months, never below zero
- Downtime if kept = Days off the road × Margin lost per off-road day
- Cost of keeping = Depreciation if kept + Maintenance + Fuel + Downtime if kept
- Depreciation if replaced = (Replacement price − Replacement resale) ÷ Holding period, never below zero
- Cost of replacing = Depreciation if replaced + Replacement maintenance + Replacement fuel
- Annual saving from replacing = Cost of keeping − Cost of replacing
- Maintenance break-even = Cost of replacing − (Depreciation if kept + Fuel + Downtime if kept), reported as zero if negative
Assumptions and limits
- The replacement is assumed to do the same work over the same distance. If it carries more or runs a different duty cycle, this comparison is not the one you need.
- Financing is excluded on both sides. Buying outright and taking a lease are different decisions with different cash profiles, and folding them in here would hide that.
- Replacement maintenance is a flat annual average. Real maintenance on a new vehicle is near zero under warranty and then climbs, so the first year looks better than this model shows.
- The old vehicle's costs are next year only. A vehicle kept for three more years usually gets worse each year, so re-run this every twelve months rather than treating one answer as settled.
- Nothing here values reliability that cannot be priced: the customer you keep because the vehicle turned up, or the driver who stops requesting a different truck.
- Tax treatment, capital allowances and grant schemes are ignored entirely. They move real decisions and vary by jurisdiction.
Why a paid-for vehicle feels cheaper than it is
The instinct to keep an old vehicle comes from a real observation: there is no monthly payment attached to it. Nothing leaves the bank account on the first of the month. The cost has already been paid, so it feels like the vehicle now runs for the price of fuel.
It does not. A vehicle worth eighteen thousand today and fourteen thousand next year cost four thousand to own for the year, and that is before it turned a wheel. That cost is invisible because it arrives as a smaller number on a valuation you never look at, rather than as an invoice. This calculator forces it onto the page next to everything else.
The year the maintenance curve crosses the depreciation curve
The economics of a vehicle move in opposite directions over its life. Depreciation is steep early and flattens as the vehicle ages, because there is progressively less value left to lose. Maintenance goes the other way: cheap under warranty, then climbing as components reach the end of their design life.
Somewhere those lines cross, and shortly after that the total annual cost of ownership starts rising again. That crossing point is the economic replacement moment, and it is rarely where the depreciation schedule in the accounts says it should be. Duty cycle decides it. A tipper on a quarry haul reaches it years before an identical chassis doing motorway trunking.
The one figure that reveals it is the maintenance break-even output. It tells you how much you could spend on the old vehicle before keeping it becomes the more expensive choice. When that number drops below the quote sitting on the workshop manager's desk, the argument is over.
Downtime is why fleets replace late and pay for it
An ageing vehicle does not fail politely at a service interval. It fails on a Tuesday, loaded, forty kilometres from the depot, and the cost of that is not the repair bill. It is the recovery, the missed drops, the driver paid to stand next to a truck, and the vehicle you had to hire because the job still had to happen.
Those costs are almost never posted against the vehicle. They land in operations, in hire, in overtime, in a customer credit. So the vehicle's cost record looks tolerable right up until the moment the fleet manager cannot remember the last week it worked five days.
The off-road days field exists to drag that back onto the vehicle where it belongs. If you would rather see cash costs only, set the margin field to zero and read the result knowing what has been left out.
Frequently asked questions
Ask the dealer or auction house you would actually sell through, and ask for a figure at next year's mileage rather than today's. Trade guides are a reasonable second choice. If nobody will give you a number, that is itself informative: a vehicle with no visible market is one where the depreciation argument for keeping it has already run out.
Then one of your inputs is wrong, and it is usually downtime. Count the actual days it was unavailable last year, including the days it sat waiting for a part, and price them at what the vehicle earns rather than at the repair cost. Fleets systematically underestimate this field because those costs never appear on a document with the vehicle's registration on it.
Only roughly. You can put the electric vehicle's energy cost into the replacement fuel field, but the model has no view on charging infrastructure, depot electrical work, range constraints on your routes, or a residual value with far more uncertainty than a diesel of the same age. Use it for a first pass and then a dedicated comparison for the real decision.
Because it would answer a different question. Keeping an owned vehicle and financing a new one differ in cash flow, in balance sheet treatment, and in what happens if volumes fall. Mixing that into the same figure hides the economics of the vehicle itself. Establish which vehicle is cheaper to operate first. Then decide how to pay for it.
Once a year per vehicle, and immediately whenever a large repair is quoted. The quote is the moment the decision is live and the moment the information is best: you know the exact cost of keeping the vehicle on the road for another year, because someone just wrote it down for you.
Stop estimating. Measure it.
Vehicle Replacement Calculator gives you the arithmetic. Fleet Management Software gives you the live numbers from your own fleet.