It was while bending suggestively over the open bonnet of a 1976 Chevrolet Camaro that Megan Fox first shot to fame. That was two years ago, when Fox starred in the first Transformers film, and she’s since been crowned “the sexiest woman alive” by FHM magazine.

The sequel is out next month and Fox, 23, doesn’t disappoint. This time she can be found straddling a souped-up motorbike, wearing a teeny pair of shorts and a body-hugging T-shirt. Fox, with her Angelina Jolie pout and hour-glass figure, is not just feigning a love of motorbikes, she’s got one — albeit newly acquired — and not a girlie one at that: a 120mph Ducati Monster 696.

“I dropped it the first time I tried to ride it,” she admits. “I’m still learning how to ride.”

Fox is just as careful not to overstep her abilities when it comes to her career. She might not fit the butter-wouldn’t-melt mould of stars such as Anne Hathaway and Keira Knightley, but she reckons she’s a role model of sorts for young women.

“It depends on what your idea of a role model is,” she says. “If your idea of a role model is somebody who’s gonna preach to your kids that sex before marriage is wrong and cursing is wrong and women should be this and be that, then I’m not a role model. But if you want your girls to feel strong and intelligent and be outspoken and fight for what they think is right, then I want to be that type of role model, yeah.”

Fox reportedly turned down the chance to take over from Jolie (the two are strikingly similar, down to their mutual love of tatoos) as Lara Croft in the Tomb Raider series, and says she has no intention of starring in a Wonder Woman movie, despite recent speculation.

“Wonder Woman is a lame superhero,” she says, clearly unfazed at the thought of ruling herself out of a potentially career-making franchise. “She flies around in her invisible jet and her weaponry is a lasso that makes you tell the truth. I just don’t get it. Somebody has a big challenge on their hands whoever takes that role but I don’t want to do it.”

Growing up in rural Tennessee and Florida, Fox trained as a dancer before winning a string of prizes at the 1999 American Modelling and Talent Convention in South Carolina. Aged just 16, with a few modelling assignments under her belt, she decided to launch her acting career. Flimsy qualifications you might think, but Fox has a straightforward, no-nonsense attitude to her world of work. “Hollywood is the most superficial thing you could possibly be a part of,” she says. “And if I weren’t attractive I wouldn’t be working at all.”

Ask if she’s afraid of typecasting and she pouts defiantly. “Getting typecast as what? Attractive? How bad is that?” she counters. “That’s not really a bad thing. If people want to look at me like that I find it flattering. And it gives me an advantage because people don’t expect anything from me. If I show up and give any sort of performance at all, even a mediocre one, everyone will walk away going, ‘Holy shit! Megan did a great job in that movie!’ So I’m an overachiever just by default because of the category I’ve been put in.”

Fox’s first screen role was in a children’s film starring the Olsen twins in 2001, followed by several TV appearances, then a supporting role alongside Lindsay Lohan in Confessions of a Teenage Drama Queen, in 2004. It wasn’t until Transformers, playing the feisty love interest, that she escaped the teen movies and started to make a name for herself.

Now she’s looking for something beyond playing the attractive sidekick. “I’ve never given anyone a reason to praise me for my talents so to sit and complain about why people don’t recognise me as an actress is [wrong]. It’s my responsibility to prove to them that they should. I need to do things where I can actually develop characters. But at the same time I don’t mind these kind of movies. I love watching them.”

Transformers: Revenge of the Fallen, produced by Steven Spielberg, which opens in UK cinemas on June 19, is unlikely to change anyone’s perceptions. But next up is Jonah Hex, a western, due for release next year, which will give Fox the chance to test her talents against the acting heavyweights John Malkovich and Josh Brolin.