Go in daylight if you can. Artificial light hides colour differences and small dents. Walk around once before you talk about price.
Body and glass
Look along each side for waves in the paint. Open every door and the boot. The gaps should be similar from side to side. Check the windscreen for chips in the driver’s view, and the tyres for uneven wear.
Inside
Sit in the driver’s seat. Does it wear where you would expect for the miles? Try the windows, the heater, the lights and the locks. A musty smell can mean water, not just old mats.
Paperwork
Ask for the service record and any invoices. A full book is better than a promise. The V5C should match the car in front of you. We do not show the registration on this demo site. On a real car, you would want it before you pay.
The drive
Listen on a cold start. Try a hill and a bit of rough road if the route allows. Brakes should pull up straight. If the seller will not let you drive, that is a reason to leave, not a detail to negotiate.