Buying a used car is one of the largest purchases most people make, yet many buyers skip the crucial inspection step. Taking time to examine the vehicle yourself—or bringing a trusted mechanic—can reveal hidden problems that affect safety, reliability and cost of ownership. This guide walks you through the essential checks that separate a sound purchase from a financial headache.
Check Paint and Panel Alignment
The paint finish tells a story of whether the car has been in an accident. Start by standing back and observing the overall colour consistency. Overspray—paint on rubber trim, window edges, or under the door sills—indicates bodywork was done after factory. Walk around the car in sunlight and look for colour variations or a slightly raised sheen, which signal respraying.
Panel gaps should be even. Use your fingers to feel the gaps between the door, bonnet, boot and body panels. Consistent gaps suggest no collision work. Misaligned panels or one panel that sits lower or higher than its neighbors point to impact damage. Also check that the protective film under doors and in engine bay hasn't been disturbed or fully removed and replaced, which is common after repairs.
Inspect for Structural Damage
Structural damage is where collision injuries hide. Get underneath the car and examine the radiator core support—the horizontal bar in front of the radiator—for straightness. A bent or replaced support is expensive to repair and often indicates a front-end impact.
Check the strut towers, which are the pillars inside the engine bay at the front corners. They should be perfectly vertical and unpainted underneath. If they've been rewelded or show signs of cutting and re-welding, the car has suffered serious damage. Run your hand along the suspension mounting points and frame rails along the undercarriage. Feel for welds that aren't factory smooth, paint coverage where there should be bare metal, or hammer marks indicating straightening work.
Look for Rust and Water Damage
Inspect under the carpets and floor mats—this is where water damage goes unnoticed. Lift the carpets in the passenger area, boot and under the seats. Look for rust spots, discolouration or a musty smell. Check the spare wheel well, the lowest point where water collects. Rust here is a serious sign that the car has been in standing water or has chronic moisture ingress.
Examine seals around windows and doors. Cracked or deteriorating rubber seals allow water inside. Look along the bottom of doors for rust bubbling through the paint. Check the roof gutters and the junction between the windscreen and the body. Also inspect drain holes in the doors—if they're blocked, water accumulates inside the door panels and causes rust from within.
Evaluate Engine and Fluid Condition
Start the engine and let it idle. The oil should be relatively clean and amber-colored. Pull the dipstick, wipe it, reinsert and remove it again. Dark or black oil suggests the oil hasn't been changed recently. Milky or foamy residue on the dipstick or under the oil cap indicates water in the engine—a sign of a blown head gasket or internal cooling system failure. This is a costly problem.
Check the coolant by looking through the plastic reservoir. It should be clear and brightly coloured—typically green, pink or orange depending on type. Cloudy, rusty-coloured or oily coolant suggests contamination or mixing of incompatible types. Low fluid levels across the board may indicate leaks. Smell the transmission dipstick as well; healthy transmission fluid has a neutral, oil-like scent. A burnt smell means the gears have overheated, likely from repeated hard driving or a transmission fault.
Conduct a Thorough Test Drive
Cold-start the engine from a stop. Listen for rough idling, misfires, or knocking. The engine should settle into a smooth, even rhythm within seconds. Watch the warning lights on the dashboard—all lights should illuminate when you first turn the ignition on, then extinguish once the engine starts. Any light that stays on (check engine, ABS, oil pressure, battery) signals a problem.
On the road, test the brakes from high speed. The pedal should feel firm and the car should stop straight without pulling to one side. Brake pull indicates uneven wear or caliper problems. Turn the steering wheel lock-to-lock at low speed and listen for grinding or clicking, which suggest bearing wear or CV joint damage. Listen for vibration in the steering wheel during braking—a sign of warped brake discs. Shift through all gears and note any hesitation, clunking or slipping. The transmission should engage smoothly.
Verify Odometer and Wear Patterns
Compare the odometer reading to the condition of wear items. Check the steering wheel rim, gear stick and brake pedal. These wear consistently with mileage. A low odometer with a visibly worn steering wheel suggests the mileage has been tampered with. Inspect the seat bolsters and seat belts for wear patterns that match the claimed mileage. Pedal pads should show corresponding wear; a high-mileage car will have thin, worn pedals.
Look at the service records if available. Regular oil changes and scheduled maintenance indicate an owner who cared for the vehicle. Gaps in service history or no records at all is a yellow flag, especially for cars over five years old.
Read the Diagnostic Codes
Before finalizing an offer, connect an OBD2 diagnostic scanner—inexpensive devices available at any car shop or online. The car should have no faults stored in memory. Recently cleared codes are a red flag because they suggest the seller tried to hide a problem before the sale. Codes about emissions, catalytic converters, oxygen sensors or the fuel system are common and often repairable. Structural or gearbox codes are more serious.
Write down any codes you find and research them. Understanding what the diagnostic trouble codes mean gives you leverage in negotiating price. A car with multiple different codes across different systems may have been treated unkindly or require expensive repairs soon.