[champignon]

Carfax and the other services' reports are often incomplete.

I would not buy a used car without researching at least the Carfax report, but I would not assume that such a report would be comprehensive, nor would I assume that the report was a substitute for normal "due-diligence."

This means, from my own bad experiences, never buy a car sight unseen unless the seller is 100% verifiable and you get the car inspected. Generally, I'd avoid sight unseen cars altogether, however if you were looking for an unusual or hard to find recent model year vehicle, and it was being sold by a BMW dealer as a CPO, and you could verify that the dealer was well regarded, then I might possibly take the risk. But that is as far as I would go on a long distance sale. Otherwise, fly to get the car before paying for it, take to be inspected, and only then decide if you want to complete the transaction.

If it is a local sale then the same general advise applies, check out the car yourself, drive the car yourself, check out the repair records, then get it inspected yourself before turning over your money.