A 1957 Ferrari 335 Sport Scaglietti has been sold at auction for$35,711,359 (including the buyer’s premium). The car was auctioned by the Artcurial Motorcars Retromobile house and it is billed as most expensive car to ever be sold at auction. 

The bidding for this 1957 Ferrari 335 Sport Scaglietti started at $22.3 million and within a minute the price had jumped to $29 million. After ten minutes a mysterious "international bidder" made the winning bid.

This 1957 Ferrari 335 Sport Scaglietti has an interesting history. It competed in the Sebring 12 Hours in March 1957 and finished sixth. The model also came in second place at the Mille Miglia and become the first model in history to have an average lap speed of over 200 kilometers per hour at the Le Mans 24 Hours. 

More than that, Sir Stirling Moss drove the car at the Cuba Grand Prix in 1958. The car was sold to Pennsylvania architect Robert N. Dusek in 1960. After ten years the 1957 Ferrari 335 Sport Scaglietti was sold to Pierre Bardinon who is a noted collector.
 
 

Source: Artcurial