What a vehicle actually costs you
Total cost of ownership is every dollar that leaves your hands because you own this vehicle, minus every dollar that comes back when you sell it. It answers a question the sticker price cannot: over the period you plan to keep it, what is this thing going to cost, and per mile driven, is that reasonable?
Depreciation is usually the largest single item, and it is invisible. Nobody writes a cheque for it. It shows up once, at the end, as the gap between what you paid and what someone will give you — and by then the decision that caused it was made years earlier. In the worked example below it is $24,000 of a $52,263 total, more than three times the fuel bill.
Finance interest is the cost of the loan, not the loan. This is where most home-made spreadsheets go wrong. Adding up sixty monthly payments and calling that a cost double-counts the vehicle, because the principal inside those payments is the purchase price, which the depreciation term already handles. Only the interest is new money. In the default example the loan costs $6,263 over five years, which is more than the annual insurance premium and nobody notices it.
Cost per mile is where the comparison lives. Total cost tells you what you can afford; cost per mile tells you whether it is efficient. And because a large part of the cost is fixed per year rather than per mile, cost per mile falls steeply with annual mileage — the same vehicle can cost $1.78 a mile at 5,000 miles a year and $0.58 at 20,000. That is why a low-mileage driver should worry about depreciation and insurance, and a high-mileage driver should worry about fuel and tires.
The six terms, and how to estimate each honestly
Depreciation is purchase price minus resale value, and both ends need care. Use the out-the-door price including sales tax, registration and any dealer fees, because none of that comes back. For resale, look up what the same model, at the age and mileage you will have reached, is actually selling for now — a three-year-old car with 36,000 miles is the best evidence for what your car will be worth at three years and 36,000 miles. Mileage matters: high annual mileage raises depreciation as well as fuel.
Energy is the one term that is genuinely per mile. For a combustion vehicle it is fuel price divided by mpg; at $3.50 and 28 mpg that is 12.5 cents a mile. For an electric vehicle it is consumption times electricity price; at 0.32 kWh/mi and $0.16 that is 5.1 cents. Use consumption measured at the wall so charging losses are included — the EV efficiency calculator converts a trip-computer figure into that basis. Use a blended rate if you charge in public sometimes, because fast charging typically costs several times a home rate.
Insurance varies enormously by model, not just by driver, and it is the one figure you can get exactly right before buying: ask for a quote on the specific vehicle. Performance models, expensive-to-repair aluminium bodies and vehicles with high theft rates all carry premiums that surprise buyers.
Maintenance, tires and fees is a blend of scheduled service, expected repairs, tire replacement spread over its life, registration and annual property or excise taxes where they apply. Tires deserve explicit attention on heavy or high-power vehicles: a set that lasts 30,000 miles at $1,200 is 4 cents a mile on its own, and the tire tread life calculator tells you where you are in that cycle.
Finance interest is computed here by amortising the loan month by month and summing only the interest portions, stopping at the end of your ownership period if the loan outlasts it. That handles the common case of a 72-month note on a car you keep for four years.
Incentives are subtracted at face value. Only include what you will actually receive: a tax credit you cannot use because your liability is too small is not a saving.
Worked example: a $42,000 vehicle over five years
You buy at $42,000 out the door, expect $18,000 at five years, drive 12,000 miles a year at 28 mpg with fuel at $3.50, insure it for $1,600 a year, budget $1,300 a year for maintenance, tires and fees, and finance $36,000 at 6.5% over five years.
- Total miles. 12,000 × 5 = 60,000.
- Depreciation. 42,000 − 18,000 = $24,000.
- Energy per mile. 3.50 ÷ 28 = $0.125.
- Fuel over the period. 0.125 × 60,000 = $7,500, which is 2,142.9 gallons.
- Insurance, maintenance and fees. (1,600 + 1,300) × 5 = $14,500.
- Loan payment. $36,000 at 0.541667% a month over 60 months amortises to $704.38 a month.
- Interest. 704.38 × 60 = $42,262.70 paid in total, less $36,000 of principal, gives $6,262.70 of interest.
- Total cost of ownership. 24,000 + 7,500 + 14,500 + 6,263 = $52,263.
- Cost per mile. 52,263 ÷ 60,000 = $0.871.
- Cost per year. 52,263 ÷ 5 = $10,453.
Read the shares: depreciation is 45.9% of the total, running costs 27.7%, fuel 14.3% and interest 12.0%. The fuel bill — the number most buyers optimise for — is the smallest item except interest. Improving economy from 28 to 35 mpg would save 60,000 × (0.125 − 0.100) = $1,500 over five years; paying $3,000 less for the car saves twice that, immediately and with certainty.
Reading the breakdown, and what to do about it
Find your largest share and attack that. The breakdown table is the point of the exercise. If depreciation dominates, the lever is buying a vehicle that holds value or buying one that has already taken its steepest depreciation — a two- or three-year-old example of the same car. If energy dominates, efficiency and fuel price matter and the calculation rewards a more efficient vehicle. If interest is large, the lever is a shorter term, a bigger down payment or a better rate.
Cost per mile falls with mileage because most costs are annual, not per-mile. Split your own total into a fixed part (depreciation is partly fixed, insurance and fees entirely so) and a variable part (energy, tires, most maintenance). The reference table below shows the shape: at $8,000 a year in fixed costs and 18 cents a mile variable, cost per mile runs from $1.78 at 5,000 miles a year to $0.45 at 30,000.
Comparing two vehicles means running this twice. Compute the total for each with the same mileage, the same horizon and the same energy prices, then subtract. The difference is what the decision is actually worth. Where one has a higher price and lower running costs, work out the mileage at which the totals cross: divide the price-plus-financing difference by the difference in per-mile running cost, and that is the break-even distance. If it exceeds the miles you will actually drive in your ownership period, the cheaper-to-run vehicle does not pay for itself.
Be honest about resale. It is the most uncertain input and the largest term, so it deserves the most scrutiny. Run the calculation twice with a pessimistic and an optimistic resale figure and see how much the answer moves. If the decision flips between them, you do not actually know which vehicle is cheaper. The vehicle depreciation calculator models the curve directly.
What this does not include. Parking, tolls, cleaning, the opportunity cost of the capital tied up in a cash purchase, and any business tax treatment. Fleet operators should also add downtime cost, which frequently exceeds the repair bill that caused it.
How cost per mile falls with annual mileage
| Miles per year | Fixed cost per mile | Variable cost per mile | Total per mile | Total per year |
|---|---|---|---|---|
| 5,000 | $1.600 | $0.180 | $1.780 | $8,900 |
| 10,000 | $0.800 | $0.180 | $0.980 | $9,800 |
| 12,000 | $0.667 | $0.180 | $0.847 | $10,160 |
| 15,000 | $0.533 | $0.180 | $0.713 | $10,700 |
| 20,000 | $0.400 | $0.180 | $0.580 | $11,600 |
| 25,000 | $0.320 | $0.180 | $0.500 | $12,500 |
| 30,000 | $0.267 | $0.180 | $0.447 | $13,400 |
Doubling annual mileage from 10,000 to 20,000 raises the annual bill by only 18.4% while cutting cost per mile by 40.8%. Fixed costs are why.
Energy cost per mile
| Fuel economy | $3.00/gal | $4.00/gal | $5.00/gal |
|---|---|---|---|
| 20 mpg | $0.150 | $0.200 | $0.250 |
| 25 mpg | $0.120 | $0.160 | $0.200 |
| 30 mpg | $0.100 | $0.133 | $0.167 |
| 35 mpg | $0.086 | $0.114 | $0.143 |
| 40 mpg | $0.075 | $0.100 | $0.125 |
Multiply any figure by your annual mileage for the yearly energy bill. At 12,000 miles a year, one cent per mile is $120 a year and $600 over five years.
Do not count loan payments as a cost
The single most common error in a home-made ownership spreadsheet is adding up monthly loan payments alongside the purchase price or the depreciation. Those payments are mostly principal, and principal is the vehicle itself — already accounted for once. Counting both inflates a five-year total by tens of thousands of dollars and makes financing look far worse than it is. Only the interest is a genuine cost, and this calculator amortises the loan to isolate it. The mirror image also matters: if you pay cash, there is no interest line, but the capital is tied up and earning nothing, which is a real economic cost this model does not charge you for.
Where these estimates go wrong
- Optimistic resale. It is the largest term and the most uncertain. Use current asking prices for the age and mileage you will reach, not a percentage rule.
- Sticker fuel economy instead of real economy. Cold weather, short trips, roof loads, towing and a heavy right foot all cost mpg. Measure your own with the fuel economy calculator.
- Today's fuel price for a five-year horizon. Use an average you would be comfortable defending, and test the answer at a price 30% higher and lower.
- Insurance guessed rather than quoted. Premiums vary by model far more than most buyers expect, and a quote takes ten minutes.
- Forgetting tires. A heavy, powerful vehicle can go through a $1,200 set every 25,000 miles, which is 4.8 cents a mile on its own.
- Ignoring an out-of-warranty repair risk. A single major repair on a complex vehicle can exceed a year of every other running cost combined. Some allowance belongs in the maintenance line for older ownership periods.
- Counting an incentive you cannot claim. A non-refundable tax credit is worth only what your tax liability can absorb.
- Comparing over different horizons. A five-year total against a three-year total tells you nothing. Fix the years and the mileage, then compare.
How this compares to published cost-per-mile figures
Several organisations publish average ownership costs. The IRS sets an annual standard mileage rate for deducting business use of a personal vehicle, which is a single national figure intended to approximate the full cost of operating an average car — depreciation, fuel, maintenance, insurance and all. Motoring organisations such as AAA publish their own annual driving-cost studies broken down by vehicle category. Both are useful as sanity checks, and both are averages built on assumed mileages and holding periods that are probably not yours.
The value of computing it yourself is that the assumptions become visible. A published average tells you the mean; this calculation tells you what your own mileage, your own resale expectation and your own loan produce. Where your answer differs sharply from a published average, the breakdown shows why — usually annual mileage, which moves cost per mile more than any other single input.
For fleets, the same arithmetic runs per unit and then aggregates, with two additions. Downtime has a cost that often dwarfs the repair triggering it, and it belongs in the model even though it never appears on an invoice. And the replacement decision is not "is this vehicle expensive" but "is its marginal cost for the next year higher than the amortised cost of a replacement" — a comparison that usually argues for replacing earlier than intuition suggests, because a new unit's depreciation is front-loaded but its maintenance and downtime are not.
For an electric versus combustion comparison, run the calculator twice with identical mileage and horizon. The differences concentrate in three places: purchase price and incentives, energy cost per mile, and maintenance. Resale value is the wild card, because it depends on battery health expectations and on how quickly the technology moves. Do not let a favourable energy comparison hide an unfavourable depreciation one — check the shares in the breakdown table before concluding anything, and use the EV charging cost calculator to get a defensible blended rate.
Key terms
- Total cost of ownership (TCO)
- Every cost of owning and operating a vehicle over a defined period, net of what you recover when you sell it.
- Depreciation
- The fall in a vehicle's market value over the period, realised as the gap between purchase price and resale value. Normally the largest single cost.
- Cost per mile
- Total cost of ownership divided by miles driven. Falls sharply with annual mileage because much of the cost is annual rather than per-mile.
- Fixed and variable costs
- Fixed costs accrue per year regardless of use — insurance, registration, most of depreciation. Variable costs accrue per mile — fuel, tires, wear-related service.
- Break-even mileage
- The distance at which a more expensive but cheaper-to-run vehicle overtakes a cheaper but thirstier one. The price difference divided by the per-mile running cost difference.
- Negative equity
- Owing more on the loan than the vehicle is worth. Common early in long-term notes, and it means a sale requires writing a cheque.