a bid is a binding contract, in theory he should just come and pick the car up without looking over it because he has brought it already, but for any reason your description doesn't meet what your selling you can pull out. ive had a few people come and try and haggle after a auction has ended saying i didn't see that in the picture i just tell them straight i did state on the auction viewings welcomed you should have come and viewed it before you bid i state in the listings.