Ask about the paperwork first

• Is the registration book (lem tabien) in your own name? If not, whose name is it in, and is there a power of attorney?
• Is the car still under finance? If so, roughly how much is left to pay off?
• Do you have the original registration book, or does the finance company hold it?
• Is the annual road tax overdue? Several years of unpaid tax come with fines, and if it lapses beyond the deadline the registration is suspended.
• How many owners has the car had before you, and how many years have you used it?

If the answers about the paperwork are unclear, do not bother asking about condition. A car in good shape that cannot be transferred is a car you cannot buy. Details are in what you need to transfer a used car.

Ask about the car's history

• Has it ever been in a serious accident or had a large insurance claim? Where was it hit, and where was it repaired?
• Has it ever been flooded? Ask straight out.
• Where is it usually serviced, at an authorized service center or a regular garage? Is there a service book or receipts?
• What is the current mileage? Compare it with the car's age to see if it makes sense.
• Has it been converted to LPG/CNG or modified in any way? If so, is it properly recorded in the registration book?
• Is there anything you know needs fixing soon? Tires, battery, air-con, suspension. An honest seller can list them one by one.

Ask about the sale

• Why are you selling? There is no right or wrong answer, but listen to whether the answer comes easily and makes sense.
• Where and when can I see the car? Meet in daylight, somewhere you can test-drive.
• Can I take the car to a garage for an inspection before deciding? If not, ask why.
• Does this price include the transfer fee, and who pays it?

Do not negotiate on the phone before you have seen the car. You have nothing to negotiate with yet, and the seller knows it.

Listen to how they answer, not just what they say

An owner who actually drives the car can answer questions about it immediately. They know when the tires were changed, where it gets serviced, and where it got scraped. Someone who answers "not sure, come and see for yourself" to every question is often not the person who really used the car.

If the answers on the phone do not match the listing, or do not match what you see when you go to look at the car, treat it as a red flag, not a small misunderstanding.

Negotiate on what you find

Negotiation that works is not just asking for a discount. It is pointing to things you will have to pay for after buying, and asking for them to be taken off the price.

• Four tires that are expired or worn out mean the cost of a set of tires.
• An old battery, weak air-con or shaking brakes are repair costs you can estimate.
• Road tax and insurance about to expire are money you will pay in the first month.

Write the list down with rough prices, then offer a price with those items deducted. Most sellers listen to a number with a reason behind it more than to "how much can you knock off?"

The on-the-spot inspection checklist is in inspecting a used car before you buy, and flood damage is covered in how to spot a flood-damaged car.