After the 2nd night I am less overawed :)
They give a price range that they expect to get say 2500-4000. There is a reserve price hidden in that price above which they will sell the car. So even if you are the highest bidder in the range, if that price is below the reserve (which you don't know until a "selling" light comes on during bidding) you don't get it.

As a result its not a true auction, as they just set a price they want and sell the car if its above that price. You get to bargin with the seller afterwards if it doesn't reach the minimum.

Still an awesome 4litre 1990 jag, with 64'000 miles, all leather and electronics, passed on at $4000 without any other bids. A beautiful car but need a mortgage for the petrol.