When you're shopping for a used car, mileage is one of the first things you look at. A lower number feels reassuring. A higher number raises questions. But mileage on its own doesn't tell you very much — it's the context around that number that matters.
Here's how to judge whether a used car's mileage is genuinely good, and how to spot the warning signs that something isn't right.
What counts as "average" mileage in the UK?
The accepted rule of thumb is that the average UK car covers 8,000 to 12,000 miles per year. So a rough benchmark looks like this:
| Age of car | Expected mileage range |
|---|---|
| 3 years | 24,000 – 36,000 miles |
| 5 years | 40,000 – 60,000 miles |
| 7 years | 56,000 – 84,000 miles |
| 10 years | 80,000 – 120,000 miles |
Anything within this range is broadly "normal." But these averages mask a lot of variation. Diesel cars tend to clock up more miles (10,000–15,000 per year is typical) because they're often chosen by people with longer commutes. Petrol cars, especially smaller ones, tend to sit at the lower end.
A five-year-old diesel with 70,000 miles isn't high mileage — it's exactly what you'd expect.
When high mileage is actually fine
There's a persistent myth that high mileage automatically means a worn-out car. In reality, how those miles were driven matters far more than how many there are.
Motorway miles vs city miles
A car that's spent most of its life cruising at 60–70 mph on motorways has had an easy life mechanically. The engine runs at a steady temperature, the gearbox isn't constantly shifting, the brakes barely get used, and the suspension isn't hammered by potholes.
Compare that to a car used for short urban trips: constant stop-start driving, the engine rarely reaching full operating temperature, the clutch and brakes working hard, and the DPF (on diesels) never getting hot enough to regenerate properly.
A motorway car with 120,000 miles can genuinely be in better condition than a city car with 40,000.
Signs of well-maintained high mileage
- Full service history — Regular oil changes and scheduled maintenance matter more as miles add up.
- Consistent MOT mileage increases — A steady upward curve in the MOT history suggests honest, regular use.
- Few MOT advisories — A high-mileage car with minimal advisories has been looked after.
- Timing belt/chain done — On cars that require it, this service (usually due at 60,000–100,000 miles) is essential. Ask for proof.
When low mileage is suspicious
Counter-intuitively, very low mileage can be a bigger red flag than high mileage.
Genuinely low-use cars
Some cars genuinely don't do many miles — a second car used only for local shopping, or a vehicle owned by an elderly driver. These cars exist, and they can be great buys if the mechanicals have been maintained.
But be cautious. A car that sits for months at a time suffers from:
- Perished rubber seals and hoses — Rubber degrades from lack of use, not just from use.
- Corroded brake discs — Discs rust when the car sits, and that rust can pit the surface permanently.
- Flat-spotted tyres — Tyres develop flat spots from sitting in one position, especially in cold weather.
- Degraded fluids — Oil, coolant, and brake fluid all deteriorate over time regardless of mileage.
- Battery issues — Batteries self-discharge and can be permanently damaged by repeated deep discharge.
A 12-year-old car with 18,000 miles may need all its fluids changed, new tyres, new brake discs, and potentially new seals — costs that quickly eliminate the "low mileage" premium.
Clocked mileage
The more concerning reason for suspiciously low mileage is clocking. This is the practice of rolling back the odometer to make the car appear lower-mileage. It's illegal, it's fraud, and it's disturbingly common — estimates suggest there could be 2.4 million clocked vehicles on UK roads.
Clocking doesn't just affect the price you pay. It hides genuine wear and tear. A car showing 45,000 miles but actually at 120,000 may be overdue for critical services like timing belt replacement — a failure that can destroy the engine.
How MOT history reveals the truth
The single most useful tool for verifying mileage is the MOT history. Every MOT test records the car's odometer reading, creating a chain of mileage data points going back years.
Run a free mileage check and look for:
Consistent increases
The mileage should go up by a broadly consistent amount each year. A car averaging 10,000 miles per year that suddenly shows only 2,000 in one year — or 25,000 — deserves questions.
Drops in mileage
If the recorded mileage at one MOT is lower than the previous test, the odometer has almost certainly been tampered with. This is the clearest sign of clocking. Our tool flags this automatically.
Gaps in history
Missing MOT records don't always mean something sinister — the car may have been off the road (SORNed) or exempt. But gaps make it harder to verify the mileage chain, which is exactly what a clocked car's history often looks like.
We go into much more detail on this in our guide to how to spot a clocked car.
What mileage means for running costs
Higher mileage does affect some ownership costs:
- Depreciation — High-mileage cars depreciate faster, but they also cost less to buy in the first place. The sweet spot for value is often a car with slightly above-average mileage that's been well maintained.
- Insurance — Most insurers ask for your estimated annual mileage. Higher declared mileage means a slightly higher premium, but the difference is usually modest.
- Maintenance — Wear items (brakes, tyres, suspension bushings) are mileage-dependent. A higher-mileage car is more likely to need these soon.
- Major services — Timing belts, gearbox fluid, and coolant changes are all mileage-triggered. Check whether they've been done.
Use our free car valuation tool to see how mileage affects the market value of any specific vehicle.
The bottom line
A "good" mileage for a used car isn't a single number. It's mileage that's consistent with the car's age, backed up by a verifiable MOT history and evidence of regular maintenance.
A 90,000-mile car with a full service history and clean MOT record is almost always a better buy than a 30,000-mile car with no history and unexplained gaps.
Before you buy any used car, check the mileage history free — it takes seconds and could save you thousands. For a complete buying checklist, see our guide to used car checks before buying.