The auction will take place on November 21 in New York, with the 1941 Cadillac Custom Limousine just one of many spectacular consignments.
The car was delivered to the abdicated king and Wallis Simpson at New York's Waldorf Hotel, and is affectionately known as The Duchess. It was previously thought to have been destroyed, and has not been seen by the public since 1952.
The car is considered one of the finest Cadillacs ever produced, and is suitably lavish in its construction, bearing the Windsor "W.E" monogram on the door.
The story of King Edward VIII's abdication of the British throne for the American socialite is one of the most famous romances of all time, and its popularity has endured among collectors, who continue to pay top prices for items related to the pair.
In 2010, the Cartier diamond and onyx leopard bracelet that Edward VIII had made for Wallis Simpson sold for £4.5m ($7.2m), becoming the most valuable bracelet and Cartier item ever sold at auction.
The Art of the Automobile auction is set to be a spectacular event, starring a $12m+ Ferrari 250 LM Berlinetta.
Paul Fraser Collectibles is currently offering a Wallis Simpson signed letter for sale.