Steve McQueen piloted it in the movie “Bullitt,” and for the next 50 years it was mostly a ghost. Now it’s heading to auction, and the speedy dark-green 1968 Ford Mustang fastback is expected to break records when it crosses the block next week at a Mecum event in Florida.

Bravely, its owner is offering the rusty, dented, largely unrestored car “without reserve,” which means it will sell to the highest bidder — however low that bid is.

The seller, Sean Kiernan, a Tennessee horse farm owner, says he is not worried that the bid will be too low. He figures the price could approach $5 million. Certainly, he adds, the car will sell for more than the $3,500 his father, Bob, paid for it in 1974.

It took only 10 minutes of screen time — the length of Hollywood’s most acclaimed movie car chase — for the Mustang (official color: Highland Green) to achieve immortality. McQueen himself raced it through the streets of San Francisco in pursuit of ill-fated evildoers in a black 1968 Dodge Charger.