Car buying glossary

Plain-English explanations of the words you'll meet when buying a used car: on a history check, an MOT certificate, a logbook or a finance agreement.

Your Car Data guide · Updated 24 October 2026 · 44 terms

A

Advisory (MOT)

A problem the MOT tester noticed that wasn't bad enough to fail, often something wearing out. Advisories that appear year after year can mean a fault that was never fixed. MOT advisories explained.

C

Cat A and Cat B

Insurance write-off categories for cars too badly damaged to go back on the road. Cat A cars must be crushed whole; Cat B cars can have parts salvaged, but the body shell must be crushed. Write-off categories.

Cat C and Cat D

The older write-off categories used before October 2017, when they were replaced by Cat S and Cat N. You'll still see them on older cars' records. Write-off categories.

Cat N

A non-structural insurance write-off: damage to things like panels, trim or electrics, or repairs that cost too much compared with the car's value. Cat N cars can be repaired and driven. Write-off categories.

Cat S

A structural insurance write-off: damage to the car's frame or chassis, such as crumple zones. Cat S cars can go back on the road once properly repaired. Write-off categories.

Clean air zone (CAZ)

An area of a city where older, more polluting vehicles may have to pay a daily charge. In England, Birmingham and Bristol currently charge private cars. ULEZ and clean air zones.

Clocking

Illegally winding back a car's mileage to make it look less used and worth more. MOT mileage readings that go backwards are a classic sign. How to spot a clocked car.

Cloned car

Usually a stolen car disguised with the number plates, and sometimes the paperwork, of a similar legitimate car. Checking the VIN is the best defence. How to spot a cloned car.

D

Dangerous defect

The most serious MOT fault: the car isn't safe to drive until it's fixed. Ask for proof that any dangerous defects in a car's history were repaired properly. MOT defects explained.

DVLA

The Driver and Vehicle Licensing Agency. It keeps the register of vehicles and their keepers, issues V5C logbooks and handles road tax.

DVSA

The Driver and Vehicle Standards Agency. It runs the MOT scheme, and its records are the source of a car's MOT history. How to check MOT history.

E

Engine number

A number stamped on the engine and printed on the V5C logbook. If they don't match, the engine may have been replaced, which should be recorded on the logbook. How to check a V5C.

Euro 4 and Euro 6

European emissions standards. To avoid London's ULEZ charge, petrol cars generally need to meet Euro 4 and diesels Euro 6. Is this car ULEZ compliant?.

Expensive car supplement

An extra yearly amount of road tax, paid for five years, on newer cars that cost over a set price when new. How car tax works.

Exported

A record that the car has been registered as exported from the UK. A vehicle recorded as exported shouldn't normally be on UK roads, so ask the seller to explain. Shown in the full history check.

H

Hire purchase (HP)

A type of car finance where you pay in instalments and only own the car after the final payment. Until then, the finance company owns it, and it can't legally be sold without settling the debt. Outstanding car finance.

I

Imported

A car first registered outside the UK and brought here. That's not a problem in itself, but check its history covers the years before it arrived. Shown in the full history check.

K

Keeper (registered keeper)

The person or company recorded by the DVLA as responsible for the car. Usually the owner, but not always, for example with lease or company cars. Keeper history explained.

L

Logbook

The everyday name for the V5C registration certificate. See V5C.

M

Major defect

An MOT fault serious enough to fail the test. It has to be repaired before the car can pass. MOT defects explained.

MIAFTR

The Motor Insurance Anti-Fraud and Theft Register, where insurers record write-offs. A vehicle history check searches it for you. Write-off categories.

Mileage anomaly

A mileage reading that doesn't fit the rest of the car's history, such as a reading lower than an earlier one. Shown in the free check from MOT records, and cross-checked in the full history check.

Minor defect

An MOT fault that isn't serious enough to fail the test, but should be repaired soon. MOT defects explained.

MOT

The yearly test of a vehicle's safety and emissions, first due when a car is three years old. Driving without a valid MOT can mean a fine of up to £1,000. How to check MOT history.

MOT exemption

Cars over 40 years old can be exempt from the MOT if they haven't been substantially changed, so a classic car may have little or no MOT history. Have one inspected before you buy.

N

New keeper slip

The green slip from the V5C logbook that the seller gives you when you buy a car. You need it to tax the car straight away. How car tax works.

O

Outstanding finance

Money still owed on a car under a finance agreement. If you buy a car with outstanding finance, the finance company may be able to take it back. How to check for outstanding finance.

P

PCP (personal contract purchase)

A popular type of car finance with lower monthly payments and a large optional final payment. Like HP, the finance company owns the car until it's paid off. Outstanding car finance.

Plate change

A change to a car's registration number, most often a private plate being added or removed. Usually harmless, but worth asking about if it's recent and unexplained. Plate changes explained.

Police National Computer (PNC)

The police database where stolen vehicles are recorded. A stolen-vehicle check looks for a marker against the registration. How to check if a car is stolen.

Private (personalised) plate

A registration number bought to put on a car. It can't make a car look newer than it is. Private plates explained.

Provenance

A car's background: whether it's stolen, written off, has outstanding finance, how many keepers it has had and so on. The full history check covers its provenance.

R

Recall (safety recall)

A manufacturer's notice that a model has a safety fault, which franchised dealers fix for free. Check any outstanding recall has been done before you buy.

Retention certificate (V778)

The document you get when you take a private number off a car, proving you still have the right to use it on another vehicle. Private plates explained.

S

Scrapped

A record that a car has been recorded as scrapped. A car recorded as scrapped shouldn't normally be back on the road. Shown in the full history check.

SORN

Statutory Off Road Notification: telling the DVLA that a vehicle is being kept off the road. A SORN car mustn't be driven or kept on a public road, except to a booked MOT. Tax and SORN explained.

Stolen marker

A record on the Police National Computer that a vehicle has been reported stolen. Never buy a car with a stolen marker. How to check if a car is stolen.

U

ULEZ

London's Ultra Low Emission Zone, covering all London boroughs. Cars that don't meet the emissions standards pay £12.50 a day to drive in it. ULEZ explained.

V

V5C

The vehicle registration certificate, or logbook, issued by the DVLA. It records the registered keeper, not the legal owner. How to check a V5C is genuine.

Valuation

An estimate of what a car is worth, usually given as private sale, dealer and part-exchange prices. Condition, history and options all make a difference. Included in the full history check.

Vehicle excise duty (VED)

The official name for road tax. It doesn't transfer when a car is sold, so the buyer must tax it before driving. How car tax works.

VIN

The 17-character vehicle identification number, unique to each car. It's at the bottom of the windscreen, in the door frame and on the V5C, and they should all match. How to check the VIN.

W

Write-off

A car an insurer has decided isn't worth repairing, or can't be repaired, after damage, flood or theft. It's given a category: A, B, S or N. Write-off categories.

Y

YCD Score

Your Car Data's score out of 100, worked out from a car's MOT records and, in the full history check, its stolen, write-off and finance records. A guide from the records, not a mechanical inspection. Try it with a free check.