Actor/Iron Man director Jon Favreau recalls feeling very anxious during the filming of certain scenes in the film, because lead actor Robert Downey Jr. had to cause harm to one of Favreau’s classic car.

To show its fans that Tony Stark/Iron Man, Robert Downey Jr.’s character, could actually build the Iron Man suit, Favreau decided to show some of Stark’s mechanical background earlier in the film by means of car restoration.

The result was Favreau “lending” his classic 1932 Ford Lowboy Flathead Roadster to Downey Jr.

Favreau said, “They painted it for the movie… and they said, ‘Do you mind if we re-do the upholstery?’ and I said, ‘No, go ahead, whatever’s good for the movie.’ I wanted to show Robert working on an old car… and then Robert, being the method actor that he is…, was like, ‘I should be ripping the head off the engine block.’ Sure enough, he busted out the wrenches and just ripped the engine apart and I was just cringing in the corner.”

Favreau then said his actions lead to the crew staring at him as if Downey Jr. was “having a go” at his wife.