Yip it depends on where they start the bid for the car, and how many people are interested in the car, and how many are willing to go further with you on the bids...e.g
2009 Alfa Romeo Brera 3.2 Q4 red with all factory extras and glass roof...Retailed in 2009 for R520k last time I checked.
Last year at Aucor - it had about 30k on the clock, FSH, one owner - it was sold for R185000!!! That's more than 65% off the original price!
I don't know how they decide on the starting bid, i.e the starting value for a car on which people have to bid on...but its normaly your deciding factor, if the starting bid is low enough compared to the value of the car, you'll make a bid, if the starting bid is too high...you'll leave it...like it was mentioned before, you need to do homework on the car, I'd suggest going to 2 or 3 auctions just as a spectator to see how events unfold...chat to the auctioneers and get yourself aquainted with the rules etc...
Oh, also remember, the auction house fee and the VAT of 14% is NOT ADDED TO THAT SALE PRICE - so in the Alfa Brera example, its R185k + 10% for auction house + 14% for VAT!
So that Brera owner would have paid this...
R185 000 + R18 500(auction house) + 25900(VAT) - R5000(deposit to be able to take part in Auction) = R224400 So...its not really that much of a saving if you take Alfa's depreciation into consideration! So...go there looking for a car in your price range...it is absolutely vital to KNOW before hand what you can spend! And in that budget work in the auction house's price and the VAT please...I've heard many stories of people buying a car at Auctions only to find out of the supposed hidden costs...well organised Auctions like Burchmores and Aucor will inform you of this before hand...
So, be warned!