Annual mileage gaps reveal odometer fraud, neglected periods, and whether the car has been ticking up town miles or hammered on motorways.
Here's a quick, honest answer from a working UK mechanic — what causes it, what it costs to fix, and what to do next.
Spotting clocking
Check gov.uk MOT history. If 2018 reading is 80,000 and 2019 is 65,000, the odometer has been wound back. Even a 'small' inconsistency is a fraud red flag.
What's normal
UK average is around 7,500 miles per year. Diesels often double that; town cars half that. Sudden jumps from 5k/year to 25k/year suggest a former taxi or rep car not declared by the seller.
Long unrecorded gaps
Multiple years missing MOT may mean the car was off road (SORN). Check why — laid up usually means hidden problems waiting to bite.
What if MOT history shows missing years? — Pre-2005 vehicles had no online history. After 2005, gaps usually mean SORN — ask why.
Is high mileage always bad? — Not on a well-serviced motorway car. A 150,000-mile diesel with full history can outlast a 70,000-mile town petrol.
More detail on: What does MOT mileage history tell me about a used car?
The short answer above covers the usual case. Below is the extra detail a UK driver normally needs to act on it — how to narrow the fault down, what it should cost, and when it is worth paying a garage rather than carrying on. This is general guidance from a working mechanic, not a substitute for someone putting your own car on a ramp.
How the MOT actually works
The MOT is a snapshot of roadworthiness on the day, not a service and not a guarantee for the next twelve months. Defects are recorded as dangerous, major or minor, and advisories are the tester telling you something will need attention before long. You can present the car up to a month minus a day before expiry and keep the original renewal date. If it fails, you cannot drive it away except to a pre-booked repair or retest appointment.
Cheap things that fail MOTs
Every year the same avoidable items fail cars: blown bulbs, a torn wiper blade, washer fluid empty, a screen chip in the driver's swept area, tyres under 1.6mm across the central three-quarters, and a number plate that has been messed with. Ten minutes in the driveway the night before genuinely saves a retest. Registered brake imbalance, corroded brake pipes and worn suspension bushes are the ones that need a ramp.
When it is worth going to a main dealer
Three situations justify main-dealer money: an open safety recall (free), a live manufacturer warranty or goodwill claim, and coding or programming work that needs manufacturer-level software. Everything else — servicing, brakes, suspension, clutches, cambelts, diagnostics — an experienced independent will do to the same standard for a good deal less, and using an independent does not invalidate your warranty under UK block exemption rules as long as the correct parts and schedule are used.
Safe to keep driving?
Treat anything affecting brakes, steering, tyres, seat belts or visibility as stop-now, no matter how well the car appears to be driving. Overheating and low oil pressure are also stop-now: the damage curve on both is measured in minutes, not miles. Most other faults will let you drive gently to a garage, but if the car is in limp mode, losing fluid, or the fault changes how it steers or stops, get it recovered instead. Recovery is cheaper than a tow plus a new engine.
What Bob would check first
Start with the cheap, common and visible: fluid levels and their condition, tyre pressures and wear pattern, battery voltage and terminal condition, and every connector and vacuum pipe in the area of the fault. A surprising share of electrical gremlins are a corroded earth or a chafed loom, and a surprising share of running faults are an air leak downstream of the sensor doing the complaining. Only after that does anything get unbolted.
Get an answer on your own car
If you want this looked at properly for your exact vehicle, send the details and Bob will write back — make, model, engine, mileage, when the fault happens and any codes you have. You get a written reply from a qualified UK mechanic with 32 years on the tools, not a chatbot, and your money back if he cannot help.
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