Just been reading about ebays policy.
It states that if the car was not as described/advertised then you are not obliged to pay.
If for example the sellers says 'car runs fine and all electrics work',
then when you get there the cars got blue smoke coming out the exhaust, and the electric windows do not work - then plain and simple - you do not have to pay.
Some people say, you should have asked the seller more questions.
But it's ebay policy that whatever is advertised should be a true depiction of the item. Therefore it's not really the buyers job to ask 101 questions to try and attain information out of the seller, especially if the seller knowingly with-held information on the advertisement.
What if you did pay for the car, then on the journey back, you realise the windows do not work, or the car overheats?
Then you would have wished, you didn't pay the full price, BEFORE checking out the car - this is why there is a an ebay policy for this.
However if everything is as described then you have to pay.
(Which I hope is the case)