Confirm the model and trim
Check that the VIN on the car matches the registration document, and write down the model, body style, engine, gearbox and trim level. Badges for a sportier version are easy to fit later, so ask which document shows the trim described in the advert, and compare the seats, wheels and interior details with that version.
Check the roof and electrical equipment
On a convertible, ask to see the roof open and close fully and note any repairs to the mechanism. Go through the climate control, seat heating, power seats and audio system item by item. Record what works today and what the seller says was fitted from new, without assuming that the two are the same.
Collect the history
Ask for invoices for engine, gearbox and suspension work, and note any parts that were replaced with non-original components. Older cars often have gaps in their records, so write down what is missing rather than guessing. An equipment list organises the original specification; a qualified inspection is needed to judge the condition of the car today.