How many kilometres a year is normal?

As a rule of thumb, the average annual mileage of a passenger car in Europe sits in the order of fifteen thousand kilometres. That is a mean across very different kinds of use and is therefore good for one thing only: a rough plausibility check. A six-year-old car showing around ninety thousand is unremarkable; one showing twenty thousand and one showing two hundred and fifty thousand are not — both need an explanation, and both often have a good one.

The spread around that mean is enormous and follows three things above all: where the keeper lived, what drives the car, and what it was for. A car registered in a city with dense public transport covers little; one from a commuter region without a rail link covers a lot. Diesels average more than petrol cars because they were mostly bought by high-mileage drivers — that is precisely where they pay.

That is why the annual figure in an advert helps less than the question of who owned it. A sales rep's car, a family's second car and a car from an estate are in three different conditions at the same mileage, and the difference between them is bigger than the difference between two model years.

Wear does not accumulate evenly with distance. An engine wears disproportionately in the first minutes after a cold start, while the oil is still cold and thick and fuel condenses on the cylinder walls. Clutch, brakes and suspension wear many times faster per kilometre in town than on a motorway. A gearbox shifts ten times as often in traffic.

From which follows a rule that contradicts most advert comparisons: a car with high motorway mileage can be in noticeably better condition than a town car with half as much. A hundred and eighty thousand kilometres covered by a rep on three long runs a week are gentler on the mechanicals than sixty thousand made up of a four-kilometre commute.

You can see it on the car, not in the advert. Stone chips on the front and windscreen, an evenly worn set of tyres and an interior that looks barely used point to long runs. A worn driver's seat bolster, a polished gear knob, parking scrapes on both bumpers and heavily grooved discs point to short trips. Ask as well what route the previous keeper drove — the answer is rarely invented, because nobody expects it to matter.

The assumption that less is always better is the most expensive mistake in this field. A car that stands ages in a different way, and that way is less well documented because it is not measured in kilometres. Damage from long periods of standing usually appears after the purchase, and it appears all at once.

Rubber, fluids and anything that lives on movement suffer most. Tyres age by years regardless of tread depth; brake discs seize with rust and go out of true at the first hard stop; seals harden and start to weep; brake fluid takes up water; fuel ages, and on petrol cars deposits form in the tank and lines. The starter battery tolerates standing worst of all.

Mileage costs you in two places: at resale and at the next big maintenance item. The first is a market convention, the second is engineering. Both can be worked out in advance, and that calculation matters more than comparing two adverts.

On the market the price does not fall evenly but in steps at round numbers, because that is where buyers' filters sit. A car just below such a threshold therefore trades expensively relative to its condition, one just above it cheaply. Deliberately buying across a threshold gets you the same wear for less — and you sell it on later at the same discount.

Technically, what counts is not the reading but the distance to the next appointment. So do not ask “how many kilometres?” but: when is the cambelt due, how much life is left in brakes and clutch, when is the next official inspection? A high-mileage car with everything freshly done can be the cheaper choice than a low-mileage one where everything falls due at once.

On an electric car the question shifts. The drivetrain has few moving parts, regenerative braking spares the friction brakes, and there is no oil change; kilometres accordingly affect the mechanicals less. What counts is the state of the traction battery — and that does not depend on distance alone.

A lithium-ion cell ages along two paths at once: through charge cycles and through time, with temperature and the state of charge while parked accelerating the time-dependent part. A high-mileage car that mostly operated in the middle of its charge window and rarely saw a rapid charger can therefore be in better shape than a low-mileage one that stood fully charged in the sun for years.

In practice: on an electric car a battery condition report replaces the debate about mileage. How to obtain one and what the figures mean has its own article in this guide.

Set the reading against the date of first registration and against the number of keepers. Six keepers in eight years at low mileage is an unusual combination; one keeper with a very high figure is an ordinary one. Contradictions between those three data points are the fastest filter there is, and it costs nothing.

If the reading does not match the wear, that is not a negotiating point but a reason to stop. Which checks apply — paper trail, wear, electronic trail — is set out in full in the article on odometer tampering and is not repeated here.

A third source is the last official inspection report. It records the reading on the day of the test, taken by a body with no interest in it. Extrapolate from there: does the distance covered since then fit the time that has passed, and fit what the seller says about how the car was used?

A large part of the young used market consists of lease returns and fleet cars, and their mileage is not an accident but a contractual figure. Lease agreements are written against an annual distance, and exceeding it costs money at the end. So cars cluster just below the agreed limit — and that is why three-year-old cars so often show readings that divide neatly by three.

For a buyer that is mostly good news. A car coming off a lease was as a rule serviced to schedule, because the contract demanded it, and it was brought up to a defined standard before being handed back. The flip side: it was driven by somebody who did not own it, and it was looked after up to the return date, not beyond it.

In practice: on a lease return, look more closely at the wearing parts that would have fallen due shortly after the hand-back date — tyres just above the legal minimum, pads near the end of their travel, an inspection coming up soon. None of that is a defect, but it is a bill that belongs in the purchase price.

Set the mileage filter wider than instinct suggests and the model-year filter narrower. The year determines the technology, the safety equipment and parts availability; the mileage mostly determines the price. Draw the mileage filter too tight and you sort out the well-kept high-mileage cars and keep the short-trip ones.

And compare remaining use rather than cars. The honest measure is what the car will cost you per year until you let it go — purchase price minus expected resale value, plus the maintenance due in that period. In that calculation a well-kept high-mileage car regularly beats a neglected low-mileage one.