How many miles is too many on a used car?

What the odometer reads at each age

These are readings taken by testers at MOT, not estimates, from DVSA’s anonymised test results for 2025 (3,393,731 tests in Great Britain, a sample of the year’s tests). The middle half of cars of an age sit between the two figures given, and that is the range in which a car is simply ordinary for its age.

• Five years old: typically 38,570 miles; the middle half read between 26,228 and 54,271.
• Ten years old: typically 74,057; the middle half between 55,167 and 95,588.
• Fifteen years old: typically 96,317; the middle half between 72,533 and 124,933.

Above the upper figure for the car’s age is high mileage; below the lower figure is low. For any other age, put the year and the reading into the mileage checker. What low mileage costs in money is a separate question, answered in what counts as low mileage for the money.

So is 100,000 miles too many?

It depends on the age, which is the whole point. On the readings above, 100,000 miles is high mileage for a car 3 to 10 years old, because it is above the upper quartile for those ages, and ordinary for a car 11 to 25 years old, because it is inside the middle half. The same odometer reading is a warning on one car and unremarkable on another.

Does high mileage make a car fail its MOT?

Mileage is not a fault, but it does move the odds, and the effect can be measured without the usual trap. Comparing a high-mileage car with a low-mileage one mostly compares an old car with a young one, so the table below holds the age still: it is every 10-year-old in the sample, by odometer reading. A 10-year-old on 0k–20k miles passed its MOT first time 90.2% of the time; the lowest band, 120k–140k, passed 71.4%.

Read it as a national rate for cars of that age and mileage, not as a prediction for the one in front of you: it says where the odds sit, and a service history says far more about a particular car.

How far each kind of car is driven in a year

One thing the odometer cannot tell you is how the car was used, and petrol and diesel cars are used differently. The Department for Transport’s National Travel Survey measures how many miles the average car is driven in a year, across all ages:

A diesel is driven about 1,800 miles a year more than a petrol car on these figures, which compounds. It is why a diesel sitting near the top of the ordinary range for its age is less unusual than a petrol car sitting there — and why neither is a verdict on its own.

Why very low mileage is not automatically good

A car well under the typical reading for its age has spent that time doing something, and the usual answer is short journeys or long periods parked. Both cost something, and neither shows on the odometer.

• Short journeys. The engine and exhaust never reach full operating temperature. On a diesel that is the classic case in which the particulate filter does not regenerate properly, and on any engine it means more of the wear happens during cold running.
• Service items with a time limit as well as a mileage limit. Cambelts are the obvious one: manufacturers specify an interval in years as well as in miles, and a car that covers almost nothing can be years overdue while looking barely used. The same applies to brake fluid and coolant.
• Parts that age on the calendar. Tyres, rubber hoses and seals perish with time rather than with distance, and brake discs corrode while a car stands.
• A gap in the record. A car that has stood for a long time may have missed services and tests, and the reason it stood is a fair question to put to the seller.

None of this makes a low-mileage car a bad buy. It makes the service dates the thing to read, rather than the odometer. A low-mileage car with the belt done on schedule and a clean record is exactly what it appears to be.

Ten years old is the fleet average, not the old end

The average licensed car in the UK is 10 years old, on Department for Transport vehicle licensing statistics for the end of 2025. A car of that age is therefore ordinary rather than exceptional, and age on its own carries no more verdict than mileage does. What changes with age is that the evidence gets longer: more test results, more advisories, more invoices, more to read before you commit.

What matters more than the number

Mileage is the cheapest thing to look at and the least informative. Three other things tell you more, and all three are free to check.

• Service history. Stamps, and better still the invoices behind them. Look for the expensive scheduled work being done on time rather than for an unbroken run of oil changes.
• The pattern of MOT advisories. An advisory is not a failure; it is a note that something is wearing. The same advisory repeated across several years is the useful signal, because it shows something was flagged and left. See what an MOT advisory means, and the categories cars actually fail on in why cars fail the MOT.
• Evidence the mileage is genuine. Covered in the next section. A reading you cannot corroborate is not a low mileage; it is an unknown one.

DVSA recorded an initial failure rate of 27.51% for classes 3 and 4 in 2025/26. That is a national rate across every initial test in Great Britain, not the chance that the car in front of you will fail.

Checking the mileage is genuine

A mileage reading is taken at every MOT test and published free, which gives you a dated sequence to check the odometer against. This is the single most useful thing you can do with a registration number before you view a car.

• Readings should rise steadily. A reading that goes down needs an explanation.
• A long flat period followed by a jump is worth asking about, and so is an annual figure far out of line with the rest of the car’s life.
• Cross-check the mileages written on service invoices and stamps against the same sequence. Two independent records agreeing is much stronger evidence than either alone.
• The record starts at the first test, which is the third anniversary of registration in Great Britain and four years in Northern Ireland, so the earliest years of any car are not covered.

If the odometer and the published record cannot be reconciled, the car may not be as described. The Consumer Rights Act 2015 gives a short-term right to reject within 30 days when goods are not as described, and that applies to a car bought from a trader anywhere in the UK. Either way, a mileage you cannot corroborate is a reason to walk rather than a price to negotiate.

The mileage record itself is free from the GOV.UK MOT history service, which you search with the registration number; the MOT check tool here is a different thing, working out from the dates when a car’s next test falls due.