Mileage is the first number most buyers look at — and often the most misunderstood. A high figure isn't automatically a deal-breaker, and a low one isn't automatically a bargain. What matters is how those miles were covered and how well the car was looked after along the way.

Quick answer: There is no single "too many" figure. As a rule of thumb an average car covers around 10,000 miles a year, so compare the odometer to the car's age. A well-serviced car with full history and higher miles is usually a safer buy than a neglected low-mileage one. Always check the recorded mileage against the MOT history for signs of clocking.

The 10,000-miles-a-year rule of thumb

The quickest way to judge mileage is to weigh it against age rather than reading it in isolation. A common benchmark is roughly 10,000 miles per year, so a five-year-old car with around 50,000 miles sits about average. Noticeably below that could point to light use; well above it suggests heavy commuting or motorway work.

Treat this only as a starting point. "Average" tells you nothing about whether the car was maintained, and two cars on identical odometers can be in completely different condition. Use the rule to frame your questions, not to answer them.

Why service history matters more than raw mileage

A full, stamped service history is a stronger signal of a car's health than the number on the dash. Regular oil changes, cambelt replacements at the right intervals and prompt repairs keep an engine and gearbox healthy well beyond 100,000 miles. A car that has skipped services can be tired and expensive at half that.

When you view a car, ask for the service book, invoices and MOT certificates. Gaps in the record, vague explanations or missing major-service items such as a timing belt should give you pause, whatever the mileage reads.

High mileage vs low mileage: the trade-offs

Consider two cars. The first is a garaged, one-owner motorway car with 100,000 miles and a full service history. The second is a 30,000-mile city car used only for short, stop-start school runs. The high-mileage motorway car may well be in better mechanical shape: steady cruising is gentle on an engine, whereas constant short trips never let the engine reach full operating temperature, which can accelerate wear and clog components over time.

This is why context beats the headline number. How the miles were driven — long steady runs versus short cold trips — often tells you more than the total itself.

Petrol, diesel and EV: mileage considerations

The fuel type changes how you should read the odometer:

  • Petrol. Generally the most forgiving over mixed, lower-mileage use. Well suited to shorter journeys and stop-start town driving.
  • Diesel. Built for high-mileage motorway work, but ill-suited to short urban trips. Diesels rely on regular long runs to keep the particulate filter clear, so a low-mileage town diesel can suffer more than a high-mileage motorway one.
  • Electric. Here the priority shifts from engine wear to battery health. Focus on how the pack has been charged and its remaining capacity rather than miles alone, and ask whether any manufacturer battery warranty still applies.

What high mileage means for price and reliability

Higher mileage pushes the price down, which can make a well-kept car excellent value. Provided the history is full and the car drives well, more miles simply means a lower purchase price and, often, more predictable maintenance.

The trade-off is that higher-mileage cars are closer to wear-and-tear jobs — clutches, suspension bushes, tyres and other consumables. Budget for these, and the saving on the purchase price can still leave you ahead. Reliability tracks maintenance far more closely than it tracks the odometer.

The risk of clocking, and how to check it

"Clocking" is winding back an odometer to make a car look less used than it is. It is easier than ever on digital dashboards and remains a real risk in the used market. A clocked car can hide worn components and, in effect, charge you a premium for miles that never disappeared.

The most reliable defence is the MOT history. Every MOT test records the car's mileage, so you can plot the readings over the years. They should only ever rise. Any point where a later reading is lower than an earlier one — or an implausible jump or flat spot — is a warning sign worth investigating before you buy. A mileage check compares the recorded readings for you and flags any discrepancies in the timeline, so you are not left cross-referencing certificates by hand.

When low mileage is a red flag

Unusually low mileage is not always the win it appears to be. A car that has barely turned a wheel can develop its own problems: perished tyres and seals, seized brakes, tired batteries and fluids that degrade with age rather than use. On a diesel, persistent short journeys can cause more trouble than a high motorway total.

Very low mileage can also be a cover story for clocking, so treat a suspiciously low figure with the same scepticism as a suspiciously high one. Match the number against the MOT record and the general condition of the car, and be wary if they do not add up.

The bottom line

There is no magic mileage at which a used car becomes a bad buy. Compare the odometer to the car's age, prioritise a full service history, think about how and where the miles were covered, and confirm the reading is genuine against the MOT record. Do that, and a higher-mileage car with the right history can be a far smarter purchase than a low-mileage one with none.