There's no single trustworthy age-by-fault table
There's no official table that says "at year X, component Y breaks" — DVSA doesn't publish MOT failures broken down by vehicle age, only by defect category across the whole fleet. Several sites present their own reprocessing of DVSA's raw open data as if it carries DVSA's own authority, and those reprocessings don't even agree with each other. What we can actually say reliably: DVSA's own data on which components fail MOTs most often, UK-wide, at any age; a genuine independent survey (Which?) showing how reliability and running costs really shift across three age brackets — and that the shift is smaller than most people assume; and well-established wear-item lifespans that are genuinely age-driven rather than mileage-driven. This guide is organised around those three things.
Does a car really get less reliable with age?
Less than you'd think. Which?'s Car Survey (fieldwork April-June 2025, 63,334 drivers reporting on 72,470 cars) segments cars into 0-4, 5-9 and 10-15-year age bands. The headline finding: the breakdown rate only rises from 11% for cars aged 0-4 years to 12% for cars aged 10-15 years — a real difference, but nowhere near the "old car = money pit" assumption suggests. Average repair cost moves from £365 to £377 across the same brackets, and servicing cost actually comes in lower for the older bracket (£290 vs £318).
Which? also found specific well-maintained older models outperforming near-new cars outright — models over 10 years old with zero reported breakdowns in the past year and repair times far below the age bracket's average. The honest takeaway: age alone is a weak predictor of reliability. How a specific car has been maintained matters more.
0-3 years — still under warranty, low-fault years
Little typically goes wrong in this window, and most of what does is covered by the manufacturer's warranty — see our guide to used car warranty options for what's usually still in place at this age. The first MOT test isn't due until a car turns three years old.
Worth knowing even here: a HiQ Tyres & Autocare survey found roughly one in five cars aged five or under failed their first MOT — a useful myth-buster that even newer cars aren't automatically immune, though this is HiQ's own survey data, not a DVSA or government figure.
4-7 years — warranty expiry and the first wear items
Manufacturer warranty cover typically runs out somewhere in this window, and the first genuine wear items start needing attention. Batteries are a common one: RAC's own guidance puts a typical petrol car battery's lifespan at roughly 3-5 years and a diesel's at 4-6 years (diesel batteries tend to be larger and work harder), with hybrid batteries commonly lasting 8-10 years or 100,000-150,000 miles. Brake pads, discs and tyres are now genuinely wear items at this stage rather than "new car" parts.
This is also typically when the first MOT advisories start appearing on a car's record — see our guide to MOT advisories explained for what an advisory actually means and how seriously to take one.
8-12 years — running costs start to shift
This bracket sits across Which?'s 5-9 and 10-15-year survey bands — the honest anchor for this age range, rather than a fabricated "X% of 10-year-olds need Y repair" figure.
It's also worth knowing what actually fails MOTs most often across the whole UK fleet, at any age — DVSA's own data (FY2024-25) puts the overall Class 3 & 4 initial failure rate at 26.22%, with the leading defect categories being lighting/electrical (10.89% of tests), suspension (8.73%), brakes (6.63%) and tyres (6.39%). This isn't age-specific — DVSA doesn't publish that breakdown — but it's a genuine, checkable picture of what actually goes wrong on UK cars generally, which is more useful than an invented age-specific number.
Mileage tends to correlate with fault patterns as much as age does — a high-mileage 5-year-old and a low-mileage 15-year-old fail for different reasons. See our guide to mileage clocking and our companion piece on what mileage is too high for a used car for more on that side of the picture.
13+ years — keeping an older car on the road
At this stage the useful question shifts from "what breaks" to "what does it cost to keep going." Corrosion and general wear become a bigger factor industry-wide by this point, though there's no single official age-specific figure for exactly how much more likely — treat this as a well-established general pattern rather than a precise statistic. Which?'s own 10-15-year data still shows well-maintained examples outperforming near-new cars, so age on its own isn't a verdict.
A full service history is one of the single best predictors of which older car is a safe bet and which isn't — our companion guide to what good service history looks like covers how to actually verify one rather than take a seller's word for it. This bracket is also increasingly mainstream, not fringe: SMMT's own data puts the average UK car at 9.7 years old, with 45.7% of cars on UK roads now over a decade old.
Age or mileage — which matters more?
Both, and they're not the same thing. A low-mileage 15-year-old car and a high-mileage 5-year-old car tend to fail for genuinely different reasons — one from age-related wear on parts that degrade regardless of use (rubber seals, batteries), the other from use-related wear on parts that wear with mileage (clutch, brakes, suspension bushes). Our guide to mileage clocking and our companion piece on what mileage is too high for a used car go into this distinction in more depth.
How to check before you buy or keep an older car
For a specific car, our Comprehensive check gives you its complete MOT history, so you can see the actual pattern of advisories and failures for that car rather than relying on general age-bracket guidance. Once you know roughly where a car sits, our free check's running-costs estimator — averaging around £300 a year for maintenance across the wider UK fleet — is worth running to budget realistically, especially for an older car where maintenance costs are more likely to be front of mind.
FAQs
What breaks first on an older car?
There's no single official answer, but batteries, brake pads/discs and tyres are typically the first genuine wear items, showing up from around 4-7 years onward. Beyond that, DVSA's overall MOT data (not age-specific) shows lighting/electrical, suspension, brakes and tyres as the most common defect categories across the whole fleet.
Is a 10-year-old car still reliable enough to buy?
Often, yes. Which?'s Car Survey found the breakdown rate only rises from 11% (0-4 years) to 12% (10-15 years) — a real but small gap — and specific well-maintained older models outperformed near-new cars outright. How well a specific car's been maintained matters more than its age alone.
Do cars really get less reliable with age, or is that a myth?
There's a real effect, but it's smaller than most people assume. Age on its own is a weak predictor — service history and how the car's actually been looked after tell you more than the year on the registration plate.
Which matters more for reliability — a car's age or its mileage?
Both, for different reasons — age-related wear (seals, batteries) happens regardless of use, while mileage-related wear (brakes, clutch, suspension) happens through use. A low-mileage older car and a high-mileage newer car fail differently, not necessarily worse or better than each other.
How much should I budget for repairs on an older used car?
There's no fixed figure, but our free check's running-costs estimator puts UK average maintenance costs at around £300 a year across the fleet — a reasonable starting budget, adjusted upward for an older car with a patchy service history.
How do I check a specific car's MOT and fault history before buying it?
Our Comprehensive check shows a specific car's complete MOT history, so you can see its actual advisory and failure pattern rather than relying on general age-bracket guidance.