An original Ford Mustang GT 390 from the 1968 movie "Britannia" is selling at auction for $3.4 million.

A 1968 Ford Mustang GT 390 starring in the 1968 film "Bullitt" sold for a reported $3.4 million at a Mecum auction in Kissimmee, Florida, on Friday.

The car resurfaced at the Detroit Auto Show in early 2018, when Ford unveiled the 2019 Mustang Brit. At the time, Haggerty Insurance CEO Mikhail Haggerty said the car might be worth $4 million.

The movie car was thought to be lost for decades, but in the early 1970s it ended up in the hands of Sean Kiernan, whose father, Robert Kiernan Jr. found it in a back issue of Road & Track magazine and purchased it for $6,000. Steve McQueen, who drove the car in the movie, offered to buy it from the elder Kiernan, but he turned down the actor's offer.

The car was then buried in the family garage until Sean Kiernan worked with Ford to bring it out of hiding for the launch of the 2019 Mustang Brit, the third special edition Mustang in Mustang history.

Neither Kiernan nor his father ever restored the car or repainted it in the iconic Highland Green paint. It remained original, with the camera mounts attached to the lower part of the body. Its original condition probably made it worth much more than if Kiernan had restored it.

In addition to its promotional work with Ford, the car was circulating around. It was featured in Jay Leno's Garage, appeared at the SEMA Aftermarket Show in Las Vegas, was on display at the Goodwood Revival, and was proudly displayed on the National Mall in Washington, D.C.

The car was also sold to a buyer in the United States. There may be plenty of promotional opportunities, although it remains to be seen who the buyers will be.