Buying a car on Ebay is, to say the least, Dodgy, but can be rewarding and you can snap up a bargain.
Before i start, be cautious, dont buy anything that has "Has the occasional.." or "Sometimes doesnt.." or "slight..." - These all mean problems, before bidding send an email (Do not phone, as there will be no comeback) - Send an email THROUGH THE EBAY CONTACT CONSOLE (OR USE CONTACT SELLER TO THE TOP RIGHT OF LISTINGS) asking for a reply with the answers, before committing to a bid.
People are selling cars for various reasons, sometimes because they have a new one, sometimes because they cant afford to run it, OR it could be because it is stolen, or because it has multiple problems, or because it has 1 problem which is costly to fix (In which case it would be easily to get rid of it by saying that it occasionally...!)
Feedback means nothing unless it is related to what you're buying - Theres no logic in trusting someone because they have been selling books, when you're buying a car from them, it is totally different.
Ask all the questions you can, and get one of the big automobile associations to go check the car before bidding and committing, also call one of the the big automobile associations (You know their names) to run a check on the car before buying it, to check that it is not stolen or has credit attached to it, or debts.
Go view the car before you pay, if the seller asks that it is paid within xxx days, go see if well before the payment deadline, take cash, get a receipt if you like the car, make sure the car has been checked out before you go get it by one of the big associations, or take a mechanic with you, dont pay for it if there are problems that are not listed in the auctions, but dont just change your mind because you dont like the colour, because you need to check all this out before bidding.
Check the location before bidding, make sure its not a billion miles away, it may be cheaper to buy it locally.
Good luck with your bids on cars!