you just made it look like you had somthing to hide , start the car, if it runs sweet he has NO comeback, as he has heard it running, and he has read the description. If it is as you described it and he is happy with the comparison, then you are home and dry for 30 secs work, and actually build a bit of trust . If I turned up to buy a car off you I had bid for on ebay, I would check it over just as thoroughly as if I was buying it from the trader/local rag... it might be a binding contract, but that means your descrition has to be 100% spot on as well And if you refused to start the engine, I would have walked and had some petrol money off you for wasting my time