The New York Daily News says that the reason the sex scenes in Factory Girl starring Sienna Miller and Hayden Christensen look so real is simple. They are real. The report says:

“It’s not simulated.” the insider said. “They’re really doing it” … At the movie’s premiere on Monday, director George Hickenlooper told the News: “Sienna and Hayden grew close during the filming. It was an emotional experience for all of us.” As for whether the sex was for real, he said: “I can’t comment. You’ll have to ask Sienna about it.” Tuesday, Miller’s publicist said the lovemaking was merely good acting. “She’s just a really good actress,” the rep said.