Mileage and value: what it's really worth
Expected mileage by age, why the 100,000 threshold costs more than the 10,000 miles either side of it, and when low mileage is a warning rather than a premium.
Mileage is the second thing every buyer looks at and the number most likely to be handled badly by a dealer, in both directions — overpaying for a low-mileage car that has been standing, and underestimating how badly a five-figure odometer reads to a filtering buyer.
Expected mileage by age
The reference point is what a car of that age would normally have covered. Around 8,500 miles a year is a reasonable UK average, though it varies by fuel and body type — diesels and larger cars historically higher, small petrol cars lower.
| Age | Expected mileage | Comfortable range |
|---|---|---|
| 2 years | 17,000 | 10,000–24,000 |
| 3 years | 25,500 | 16,000–35,000 |
| 5 years | 42,500 | 30,000–58,000 |
| 7 years | 59,500 | 42,000–80,000 |
| 10 years | 85,000 | 60,000–115,000 |
A car inside the comfortable range needs no adjustment at all. The market has already priced it, and fiddling with the number introduces error rather than removing it.
The thresholds that matter more than the miles
Value does not decline smoothly with mileage. It steps, because buyers filter at round numbers.
100,000 miles is the big one. An enormous number of buyers set a hard ceiling there, either in the search filter or in their head. A car at 101,000 is invisible to them; the same car at 98,000 is not. The value difference across that boundary is far larger than the 3,000 miles justifies.
60,000 and 80,000 matter for similar reasons, less sharply. Warranty eligibility and service intervals cluster near them.
10,000 miles on a nearly-new car marks the boundary between "as new" and "used" in a lot of buyers' minds.
The practical consequence at the buying end: a car at 97,000 miles is worth meaningfully more than one at 103,000, and the auction hall does not always price that gap correctly. There is money in noticing.
At the selling end, it means you should never take a car over a threshold unnecessarily. Moving a 98,500-mile car for an unnecessary errand and putting it over 100,000 is a genuinely expensive mistake.
Adjusting, once
Where a car sits well outside the normal band, an adjustment is justified — but only once, and only if you have not already handled it.
If you found comparable sales in the same mileage band, the adjustment is already made. Adjusting again double-counts and produces a number that will lose you the car at auction or leave it sitting on the forecourt.
Where you do adjust, the shape is roughly:
- Below expected: a modest premium, smaller than instinct suggests, and less on older cars.
- Above expected: a deduction that steepens as you approach and cross the thresholds.
- Far above: on a car with 140,000 miles where 85,000 is expected, mileage stops being an adjustment and becomes the defining characteristic. Price it as a high-mileage car, not as a normal car with a discount.
When low mileage is a problem
Unusually low mileage is not automatically a premium, and experienced buyers know it.
Standing damage is real. Cars that sit deteriorate in ways that mileage does not capture — perished seals, corroded discs, tyres flat-spotted and aged out, batteries that will not hold, fluids past their life. A twelve-year-old car with 22,000 miles may need more work than one with 90,000 that has been used and serviced properly.
Short-journey wear. Very low annual mileage often means short trips, which is the hardest use for a modern engine. On diesels especially, a car that never gets warm enough to regenerate its particulate filter is a repair bill waiting to happen. Low mileage on a modern diesel deserves more scrutiny, not less.
Buyers ask why. A car with implausibly low mileage invites questions about whether the reading is genuine, and the burden of proof is on you.
The right response is evidence: full service history with dates matching the mileage, MOT records showing a consistent progression, and honest photographs. With that evidence, low mileage is worth a real premium. Without it, it is a question mark.
Clocking and how to check
The mileage record in successive MOT tests is the most accessible check available, and it is free. Look for a consistent upward progression. A reading that jumps oddly, or a gap where a test is missing, needs explaining before you buy.
Service records should corroborate. So should the car itself — a steering wheel, gear knob and driver's seat bolster worn out of proportion to 40,000 miles is telling you something.
Both taking and giving a warranted mileage matters. A car sold with mileage not warranted is worth less and should be bought as such.
Mileage against the rest of the picture
Mileage interacts with everything else, and the interactions matter more than the raw figure.
A high-mileage car with full main-dealer history and a recent cambelt is a better buy than a low-mileage car with no history at all. Buyers will tell you they want low mileage; what they actually buy is confidence, and documented history provides more of it than a small number on a dial.
For your own buying, the useful frame is: does the mileage make this car harder to sell, and if so, by how many days? A car 20% over expected mileage in a liquid segment might cost you a week. The same car in a thin segment might not sell at all.
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