Know the price before the garage does.

What the engine management light means

Steady means book it, flashing means stop — and the MOT never reads your fault codes.

DPF light on — and can you clear it?

One long drive usually does it. The manual has no entry for this lamp at all.

Why do my brakes squeal?

Morning rust, the wear indicator, or metal on metal — the timing of the noise tells you which.

Steering wheel shakes when braking?

Nearly always the front discs, worn unevenly rather than warped. One coasting test rules the brakes in or out.

Humming noise when driving?

One free test at forty miles an hour separates a wheel bearing from your tyres.

Car judders when pulling away?

Clutch, flywheel or a mounting worth a fraction of either — and reverse gear tells you which.

Soft or spongy brake pedal?

Brake fluid cannot be squashed, so a pedal that gives is a fault — and the test only fails one touching the floor.

Why does my engine rattle on a cold start?

Time it with a stopwatch. The number of seconds is the diagnosis — and the MOT never checks this.

What’s that burning smell?

Inside the cabin is the urgent one. Six smells, and the two that mean pull over.

Blue, white or black smoke?

Blue is oil, thick white is coolant, black is too much fuel — and a DPF fails on any of it.

What is that puddle under my car?

Six fluids by colour and position — and which two mean stop driving today.

What MOT advisories mean

Advisory, minor, major, dangerous — which become failures and which can wait.

How to read your MOT history

Mileage checks, repeat advisories and red flags — on your car or one you are buying.

Independent vs main dealer

Why the same job costs around half as much again at a dealer — and when they are still worth it.

What the MOT actually checks — the complete guide

Eighteen sections, one page. Every part of the test explained with the figure behind each verdict: 1.5mm of friction material, 58% braking efficiency, 1.6mm of tread, 13mm of steering play, 290mm of windscreen. Then the part nobody publishes — what our analysis of 145 million advisories shows actually happens to a car in the year afterwards.

The most reliable used cars

How often a car fails and what the failure costs turn out to be unrelated — a correlation of 0.045. Four kinds of car, not one ranked list.

Diesel vs petrol reliability

At fourteen years both fail 33.2% of MOTs — but the diesel got there on 28% more miles. Per mile, diesel wins at every age.

MOT failure rates by car

A ten-year-old Laguna fails 37.8% of tests, a Q5 17.7%. Every other ranking compares birthdays; this one compares cars.

First MOT failure rates

15.6% of vehicles fail at three years old, and vans 23.0% against 14.6% for cars. Mileage explains nearly all of the gap.

MOT advisory statistics

A third of all advisories are never repaired — 46 million warnings written and ignored. The ones drivers skip are not the ones that matter least.

What happens if you ignore an MOT advisory

A suspension advisory comes back as a failure 18.7% of the time, an oil leak 1.3%. Eight categories ranked by what ignoring each one is worth.

The most expensive things to fail an MOT

The test is capped at £54.85. The dearest thing it can find costs twenty-seven times that — and the very dearest has no price at all.

Car repair costs by age

Risk peaks at fifteen years and then falls — for everything except rust. Five categories, each with its own curve and its own cost.

The most reliable vans

Thirty-two models ranked, and a finding that undoes the ranking: the vans that start best decline fastest, at a correlation of −0.65.

Do vans fail their MOT more than cars?

A three-year-old van fails as often as a six-year-old car. The gap is widest on nearly-new vehicles and closes with age.

Buying a used van

History first, then model, then age, then mileage — close to the reverse of how most people buy. Mileage correlates with failure at just 0.333.

What to check before your van’s MOT

Three checklists, not one. What fails a three-year-old van is not what fails a twelve-year-old one, and the honest advice changes with it.

The van advisory index

A brake advisory on a van aged seven to eleven becomes a failure 13.67% of the time against 8.64% on a car — the widest gap in the dataset.

Class 7 MOT cost

Capped at £58.60, just £3.75 above a car. Which class your van needs cannot be answered from the model, whatever the lists elsewhere say.

Van repair costs — everything in one place

What van repairs actually cost, from £80 for drop links to £1,190 for a reconditioned turbo, with every price broken down into parts, workshop time and an independent garage’s hourly rate. Alongside it, the half nobody else publishes: suspension is 18.89% of everything vans fail on, and the gap between the best and worst model at the same age is 15.69 percentage points — twice the gap between vans and cars.