Running costs, honestly: what a car takes from you every year

The purchase price is the number everyone compares, and for most people it is not the largest number involved. Two cars bought on the same day for the same money can be thousands apart by the time they are sold, without either of them ever breaking down.

Nobody can tell you what your car costs. Too much of it depends on where you live, how you drive and what you insure. What can be laid out is which lines belong in the calculation, which ones people habitually leave out, and how to run the arithmetic on your own vehicle with receipts you already have in a drawer.

Depreciation is usually the biggest line

Depreciation is the gap between what you paid and what someone will give you later, spread across the years in between. It is easy to ignore because you never write a check for it. It arrives all at once, on the day you sell, disguised as a disappointing offer.

The loss is steepest early and flattens out with age. That single fact drives most of the sensible advice about buying used: a car a few years old has already had its worst years of value loss absorbed by somebody else, and the same money buys more car. Kept long enough, depreciation almost disappears as an annual cost, because a car with little value left has little left to lose.

What moves it, beyond age and mileage: how desirable the model is secondhand, whether a replacement generation has just landed, condition and history, and shifts in what buyers want from a fuel type. None of that is under your control. Two things are — buying at the right point in the curve, and keeping the car long enough that the purchase spreads thin.

The lines people do budget for

Fuel or charging	Varies more with how and where you drive than with the car itself
Insurance	Re-quote every renewal; staying put is rarely rewarded
Tax, registration, inspection	Fixed, dull, and easy to look up in advance
Scheduled servicing	Predictable if you follow the schedule, unpredictable if you do not
Tires	A set every few years; the size and rating decide the price more than the badge
Brake pads and discs	Consumables, with a wear rate set largely by your right foot

The lines people forget

• Parking — a residential permit, a workplace space, the airport for a week, the tickets you occasionally collect
• Tolls, bridges and city access or congestion charges on the routes you actually use
• Interest on the loan, which is a real cost of the car rather than part of the price
• The excess or deductible you pay when you claim, plus what the claim does to the next renewal
• Wipers, bulbs, a battery every few years, washer fluid, and the annual cost of keeping it clean
• Roadside assistance, and the rental or rides you buy during the week the car is in a shop
• Storage for the second set of wheels, if you live somewhere that runs winter tires

Finance deserves a sentence of its own, because a monthly payment feels like the cost of the car and is not. On a loan, the interest is a running cost sitting on top of the depreciation. On a lease, the payment is essentially depreciation plus interest with the guesswork removed, which makes budgeting easy and makes exceeding the contracted mileage expensive.

Cheap to buy is not cheap to own

An older luxury sedan is the classic trap. The purchase price falls to hatchback money, and every other cost stays exactly where it was: large wheels with expensive tires, big brakes, more complicated suspension, a battery the size of a briefcase, and labor times written for a complicated car. Nothing about it got cheaper except the sale price.

The same logic applies to hardware complexity generally. Air suspension, twin-clutch transmissions, turbochargers and exhaust after-treatment all do their jobs well and all add components that eventually need attention. That is not an argument against any of them. It is an argument for knowing which of them you are buying, and for pricing one or two likely repairs before you commit.

Insurance is worth checking before purchase rather than after. Ratings do not track purchase price neatly — engine output, repair cost, theft history and parts availability all feed in, and two similar-looking cars can quote very differently. Get a real quote on the exact car you are considering while you can still change your mind.

Working out your own cost per mile

1. Pick a period you have records for — twelve months is plenty, and a calendar year is easiest
2. Add every fuel or charging receipt for that period, including the awkward expensive ones on trips
3. Add insurance, tax, registration and any inspection fee
4. Add every service and repair invoice, and every consumable: tires, wipers, a battery, a bulb
5. Add parking, tolls, permits and cleaning
6. Estimate depreciation by looking up what your car sells for now against what the same car sold for a year ago in comparable condition
7. Divide the total by the miles you covered in the period

The number that comes out is usually larger than expected, and it is most useful as a comparison. It tells you whether a second car earns its keep, whether the train is genuinely more expensive, and whether a shiny replacement would actually cost less to run than what you have.

It also exposes the fixed-cost problem. Insurance, tax and depreciation arrive whether you drive or not, so a car covering very few miles a year has a brutal cost per mile no matter how frugal it is. If that is you, the savings are not in fuel economy at all — they are in owning a cheaper car, or in one fewer car.

Where the money is actually saved

• Buying after the steep part of the depreciation curve, then keeping the car long enough for the purchase to spread out
• Doing scheduled maintenance on time, because deferred maintenance is the most expensive kind there is
• Re-quoting insurance at every renewal and being willing to move
• Keeping tires at the pressure on the door placard, which costs nothing and slows their wear
• Fixing small faults while they are still small, particularly anything leaking

Run the arithmetic once, properly, with real receipts rather than estimates. It usually changes exactly one decision — which is more than most spreadsheets manage.