BEVERLY HILLS—In Iron Man 3, Gwyneth Paltrow spends some time hanging upside down, in seemingly dire circumstances, wearing only a sports bra and yoga pants. She (and her character, Pepper Potts) appears extraordinarily fit. Quarters would surely bounce off that abdomen. Why, Tony Stark (aka Iron Man), Pepper’s boss and paramour, wants to know, doesn’t she wear that stuff around the house more often?

At a hotel one recent morning, Paltrow was wearing pointy black stiletto pumps, high-waisted cropped black pants, and a one-shouldered, white sleeveless blouse that draped like an elegant scarf around her neck and down her back. Her sleek blond hair was tucked behind her ears, where what looked like tiny diamonds sparkled.

The effect was decidedly ’50s movie star, à la Grace Kelly. Paltrow’s effect on-screen, in Marvel’s third film about its billionaire-inventor superhero, is decidedly more Iron Woman.

In Iron Man 3 (which opens next Friday [May 3] ), a terrorist called the Mandarin (Ben Kingsley) comes wreaking destruction. In the mayhem, Pepper, the levelheaded CEO of Stark Enterprises who shacks up with Tony in his cliff-top Malibu pad, finally gets to, literally, wear the iron suit in the household.

“I really loved their relationship in the first movie, when she was a supplicant and cleaning up his messes,” Paltrow said. “And then to get all the way to where she is at the end of the trilogy, it was a big transformation. And I think one of the things that I love the most is that she really steps into her power.” The transformed Pepper wallops a villain or two and several times comes to the physical, not merely emotional, rescue of her flesh-and-metal man. “She turns into a superhero… Or sort of!”

Robert Downey Jr., the anxiety-ridden superhero, and Don Cheadle, who also suits up as Col. James “Rhodey” Rhodes, were seated alongside Paltrow. They began discussing how uncomfortably heavy some of the suits were that they’d worn for the films. One of his, Cheadle joked, weighed “7,000 pounds”.

“You guys are wimps, okay?” Paltrow interjected. “The suit is not that bad!”

“You never wore it! You never put it on!” Cheadle insisted. They argued playfully (or perhaps not) about whether Paltrow had worn “CGI” or the real deal. Playing peacemaker, Downey confirmed that one of Cheadle’s suits “was hard to even pick up to put on him”, while Paltrow, “in rockin’ shape, so it was nice and easy”, wore a suit “once or twice. It’s an accumulative issue,” he added diplomatically. “Thank you,” Cheadle said. “You’re welcome,” Downey replied. Paltrow laughed.

Paltrow admitted she was “uncomfortable” when producer Jon Favreau, who directed the first two Iron Man movies, gave up his chair to infamous action-movie screenwriter Shane Black, who had directed only once before (Kiss Kiss Bang Bang).

“But as we went on, I really warmed to Shane and his terrible outfits,” she said, making Downey laugh. “I think that Shane is really supertalented and he took it up a notch, which was really difficult to do, so I ended up having an incredible amount of respect for him.”

Farther down the dais, Kingsley was pondering what Paltrow had said about their director. “I only remember him being in one terrible outfit,” he said, deadpan.