No one knows who bought the original Ford Mustang hero car from 1968's Bullitt starring Steve McQueen.

Well, almost no one; the car was sold to an anonymous bidder at Mecum's Kissimmee, Florida collector car auction earlier in the month, and only Frank Mecum - the event's host - knows the buyer's identity.

"Eventually, it'll come out," Sean Kiernan - the car's previous owner - told the Detroit Free Press. "But right now, no one knows. Only Frank [Mecum]. Frank is the only one trusted to know."

The Highland Green 1968 pony car set a new auction price record for Mustang on Friday, attracting a high bid of $3.4 million, which far surpassed the previous $2.2-million record held by a 1967 Shelby GT500 "Super Snake".

The Bullitt hero car resurfaced several years ago after decades of obscurity as the film, notable for its iconic San Francisco car chase scene, approached its 50th anniversary. Then-owner Sean Kiernan, 34, inherited the car from his late father Robert, after Robert was the sole respondent to a for-sale ad placed in Road & Track magazine in 1974.

As a nod to the car's ownership history, Sean had the bidding for the highly collectible Ford Mustang start at $3,500 because that's what his father paid for it back then.

"When the auctioneer asked, 'Who will give me $3,500?' Everybody in the room raised their hand. Everybody had a chance to bid on the car," Kiernan says.

Before its public reveal in 2018, the original Bullitt Mustang underwent a mechanical restoration, and after its presentation at the 2018 North American International Auto Show in Detroit, it toured the country for two years. Sean hadn't planned to sell, but after his wife Sam gave birth to their third child, she became ill and Sean's priorities shifted.

"She had emergency surgery," Sean told the Free Press. "We wanted to tell our family story with the car but now I want to play in the dirt during the day and play with cars at night - both with my girls. Just take care of my property and cut hay. That's what I love to do."