The total price is as follows:
Bid + 16% actioneer's premium = subtotal.
Subtotal + 21% VAT of the bid + 21% VAT of the auctioneer's premium = Total price.
So for a bid/hammer price of €1000, it would be 1000 + 160 + 210 + 33,6 = €1403,6. That makes it just over 40% to add.
I went to the viewing too and I have no explanation for quite a lot of the bids. For some vehicles the bids by themselves would already be near or over the top value, let alone if you add another 40%...