Buying Guide

How to Check a Used Car Before You Buy — Complete UK Checklist

Updated October 2025 · 12 min read · Includes: online checks, viewing checklist, test drive, red flags

One in three used cars sold in the UK has some form of hidden history — outstanding finance, a previous write-off, mileage discrepancy, or something else the seller hasn't mentioned. Most buyers find out after they've handed over the money, when it's much harder to do anything about it.

This checklist is designed to catch problems before you buy. Run through it on every car, no exceptions.

Step 1: Online checks before you even visit

Do these at home, before you waste time and petrol going to a viewing on a car with a problem history.

🔍 Before the viewing

Free MOT history check (gov.uk) Go to gov.uk/check-mot-history, enter the reg. You get the full MOT history: every test, every fail, every advisory note. Look for: recurring failures in the same area, mileage that jumps backwards (odometer fraud), and whether the car has been regularly tested (gaps suggest SORN periods or high-mileage use). 🚩 Red flag: mileage discrepancy between MOT tests — suggests clocking.

Free DVLA check (gov.uk/get-vehicle-information-from-dvla) Confirms: make, model, year, colour, engine size, tax and MOT status, number of previous owners. Make sure everything matches what the seller told you. 🚩 Red flag: colour or spec doesn't match — could indicate a cut-and-shut or identity swap.

HPI check (~£20 — non-negotiable) Checks: outstanding finance, write-off status (Categories S and N), stolen flag, mileage discrepancy, number of previous keepers. Get this before you visit, not after. If the car has outstanding finance, the lender can legally repossess it from you even though you paid for it. 🚩 Red flag: any finance outstanding, any write-off category. Both require extreme caution.

Cross-check the asking price Search the same make, model, year and mileage on AutoTrader and eBay Motors. If this car is significantly cheaper than comparable examples, there's usually a reason. Not always — but worth knowing the market before you negotiate.

Step 2: At the viewing

Golden rule: Only ever view a car in daylight. Bodywork defects, rust, and mismatched paint are invisible in the dark or artificial light. If a seller insists on an evening viewing, be suspicious.

🚗 Bodywork and exterior

Walk around in good light looking for paint colour mismatches Crouch down and look along each panel from the front and rear. Even slight differences in colour, texture, or shine indicate accident repair. Some repair is fine — but it must be priced accordingly and you want to know what was repaired. 🚩 Red flag: mismatched paint on adjacent panels, especially around structural areas (pillars, sills).

Check panel gaps All the gaps between panels (bonnet/wings, boot/rear quarters) should be even and consistent. Uneven gaps suggest the car has been in a significant impact and the bodywork has been re-fitted slightly wrong.

Look for rust — especially at the sills, wheel arches, and underneath the boot Surface rust on brake discs is normal and harmless. Structural rust on the sills, floorpan, or suspension points is dangerous and potentially an MOT fail. Probe any rust with a key — if it goes through, the metal is compromised. 🚩 Red flag: rust around structural sills, floor pan, or suspension mounting points.

Check all four tyres — tread depth and condition The legal minimum is 1.6mm across the central three-quarters of the tyre width. Insert a 20p coin into the tread — if you can see the outer band, the tyre is at or near the legal limit. Also check for uneven wear, which suggests alignment or suspension problems. Budget £60–£120 per tyre to replace. 🚩 Red flag: uneven wear on inner or outer edge — steering geometry issue.

🔧 Under the bonnet

Check oil level and condition Pull the dipstick, wipe, reinsert, and check. Level should be between MIN and MAX. Colour should be amber to dark brown. Black and gritty = overdue for a change. White/milky = water contamination, potentially a head gasket issue. This is the most important check under the bonnet. 🚩 Red flag: milky or foamy oil — possible head gasket failure (expensive).

Check coolant level and colour Should be between MIN and MAX. Should be blue, green, or pink — not brown or rusty. Never open the coolant cap on a warm engine.

Look for oil leaks around the engine A clean engine bay is ideal. A slightly oily engine isn't necessarily a problem — older cars all weep a little. A heavily oil-contaminated engine has an active leak.

Start the engine cold Ask the seller not to warm it up before you arrive. Cold starts reveal problems that disappear once the engine is warm. Listen for: blue smoke on start-up (oil burning), white smoke (coolant burning — potential head gasket), or rattling on start that quietens (worn timing chain). 🚩 Red flag: blue smoke on cold start, persistent rattling, hesitation.

🪟 Interior

Test every electrical item All windows. Every light. Air conditioning (not just fan — actual cold air). Heated rear window. Heated seats if fitted. Infotainment screen. USB ports. Horn. Anything that doesn't work is your negotiating leverage — and potentially your future repair bill.

Check all warning lights extinguish at startup Turn the key to position II (engine off, electrics on). All warning lights should illuminate briefly and then go out when you start the engine. Any that stay on mean a live fault. Ask the seller to explain any warning lights that stay lit. 🚩 Red flag: engine management light, airbag light, or ABS light staying on after engine starts.

Check for damp/water ingress Lift the carpets in the footwells and boot. Wet or musty carpets suggest a sunroof seal leak, a blocked drain, or flood damage. Flood-damaged cars are a specific issue — the damp eventually causes electrical failures.

Step 3: The test drive

Do not skip this. A lot of sellers will tell you they've had the car serviced, the MOT just passed, it's perfect. A test drive is where you find out what they didn't tell you.

Drive for at least 20 minutes. Include a mix of slow town driving, a 30mph road, and motorway speeds if possible. Problems often only emerge once the car is warm.
Brake firmly. Do an emergency-type stop on a quiet road. The car should pull straight. Pulling to one side means a brake problem.
Test the clutch. On a hill, bring the clutch up slowly. Slipping = worn clutch (expensive repair).
Test the gearbox. All gears should engage cleanly. A crunchy second gear is a common fault on high-mileage cars.
Listen for vibration. Steering wheel vibration at 60–70mph suggests wheel balance or tracking issues.
Listen for suspension noise. Clunks or knocks over bumps suggest worn bushes or dampers.

Never test-drive a car you haven't insured. You're responsible for any accident in an uninsured vehicle, regardless of whether it's a test drive. Either check your own insurance covers driving other vehicles with the owner's permission, or get a short-term policy.

Step 4: Paperwork and the seller

V5C (logbook): Must be present. The name and address on the V5C should match the seller. If they're selling on behalf of someone else, find out why.
Service history: Full stamped service book with dates and mileage is ideal. Online service records from a main dealer are acceptable. No history at all is a risk — budget for a service before you drive.
MOT certificate: Keep the physical certificate for future reference.
Two keys: Most cars come with two keys from new. Missing the spare key is worth £100–£400 to replace.

Print-ready version of this checklist

The full checklist is available as a downloadable PDF on StarterMotors. Take it to every viewing.

Get the free checklist →

This guide reflects standard best-practice advice for used car purchasing in the UK. It is not a substitute for a professional pre-purchase inspection (RAC/AA inspections cost £100–£200 and are worth it on any car over £5,000). HPI check pricing approximate as of October 2025.