Penelope Cruz "cried" because of the "sad energy" in Laura Ferrari's bedroom.
The 49-year-old actress found a visit to the apartment where her Ferrari alter ego lived incredibly helpful for informing her role in the biopic because it made her understand how the woman felt following the end of her marriage and the death of her son.
She told Empire magazine: "It was a lot of colors that were supposed to be happy but to me it had a very sad energy.
"I started to cry, understanding what it would be like for this woman spending so much time hiding in that room, missing her son and missing what she had in that relationship with Enzo.
"There was something that happened to in that room and I think it also happened to Michael [Mann, director]."
The filmmaker ended up exactly replicating the wallpaper they had found in the bedroom.
Penelope said: "For us it had a meaning. We could see it there and remember the effect it had on us the first time we saw it."
The Spanish actress was determined to do Laura justice because she felt frustrated by the way she was left in Enzo Ferrari's shadow and her own contributions to their company sidelined.
She explained: "When I was doing my research, a lot of people were saying to me she had mental problems, she was just hiding at home, she was crazy — she had nothing to do with the company.
"And the more I would read about her, the more furious these comments would make me.
"She's much more important for the family than people have known or people wanted to know."