Eva Mendes, in sleeveless mauve Doris Day dress, reclines on an ornate yellow sofa like a Tinseltown odalisque. “Hey you!” she says, chuckling warmly, as I enter the opulent West London hotel suite that will serve as today's meeting place. “What you been up to since last time?!” adds the 34-year-old former model and current Hollywood player, casting our minds back to our first encounter, 18 months ago. Then, on a promotional tour for the mildly wearisome comic-book adaptation Ghost Rider (she played Nicolas Cage's love interest), Mendes was, simply, a hoot.

Fantastically indiscreet and off-message, she spoke at length, with wit and bracing honesty, about the perils of being an actress on the rise. Big dumb movies such as Ghost Rider were, she said, a necessary way to boost her profile and to allow her access to passion projects such as the exemplary New York crime thriller We Own the Night. Some of her past performances, she said, had been awful, but she was getting better. She stopped the tape and talked, off the record, about verboten sexual practices. And she flinched at the very idea of being pregnant (“I mean, seriously, I know it's supposed to be like, ‘Wow, you're so beautiful!' But dude, you're swollen, sick, you're back hurts, you can't sleep! Come on!”). In short, in a Hollywood world of PR-controlled soundbites, she was ineffably refreshing.

“Er, nothing much has changed,” I answer. Mendes nods, again warmly. “Oh, I hear you,” she says, sharing a moment. And yet, ironically, for Eva Mendes, everything has changed. In the past 18 months she has been transformed from an actress to a fully- fledged movie star. We know this because she stood toe-to-toe with Joaquin Phoenix in We Own the Night and gave a truly fearless performance therein (watch her thump Phoenix, screaming, “I f***ing hate you!” and you'll get it). We know it because she has since notched up roles in two highly anticipated forth- coming movies, the Werner Herzog-directed Bad Lieutenant: Port of Call New Orleans (opposite Cage again), and the adultery drama Last Night (opposite Keira Knightley). And we know it because she is one of the headlining female stars in another new comic book blockbuster, The Spirit (the movie she is promoting today). But we know it also, because of the other stuff. Because, like any self-respecting A-lister, Mendes spent several weeks in a rehab clinic, in Utah, earlier this year. And like any other A-lister, and perhaps not entirely unconnected with the rehab stint, she is currently brand-managed to the hilt.

Thus, a swarm of publicists buzz around the corridors outside her suite - “Remember, it's ‘Ay-va' and not ‘Eeee-va',” one warns me sternly before I enter. And even then, gasp, there's one inside, in the suite itself, Eva's personal publicist, a young woman direct from LA, who will be observing the entire meeting. Here, she sits within my line of vision, smiling, giggling at Eva's wisecracks, and occasionally offering Eva a helping hand (“There are different types of Catholics,” she says, guiding Eva through a definition of Roman Catholic). Otherwise, she stares benignly at me with a sweet, unyielding look that says, “You mention rehab, and this interview's over!”

Which is a shame. Because Mendes herself - still witty today, still gorgeous and gregarious but predominantly on-message (“Ghost Rider was an amazing experience!”) - is an eminently compelling subject. The daughter of two Cubans who emigrated to Miami before Castro's revolution, she grew up in working-class East Hollywood but somehow she came to embody that impeccable American self-belief in ultimate achievement. She says that her athletics coach, at Herbert Hoover High School in LA, was partially responsible. He instilled in the 11th grade Mendes the mantra “Never look back!” (a whizz at 400 metres, she was ultimately bedevilled by a habit of, “Looking back to see who was trailing behind me”). The mantra has since become a metaphor for her career strategy, and illuminates an inexorable rise from Calvin Klein model (she was spotted by a neighbouring photographer) to pop promo extra (see Aerosmith's Hole in My Soul) to dazzling eye-catcher in movies such as the Denzel Washington thriller Training Day or the Will Smith romantic comedy Hitch.

She says that she is solely driven by the desire to be a better performer, and that she regularly sits down with her acting coach Ivana Chubbuck (former students include Brad Pitt and Halle Berry) and skips, scene-by-scene, through her movies, allowing her onscreen self to be picked to pieces. “I don't enjoy the torture of somebody telling me how bad I was,” she says. “But I am eager to be great.”

And yet, you sense, there must be something more. With The Spirit, for instance, she says that she was drawn to playing the homicidal jewel thief, Sand Saref, because of the character's rapacious ambition. The movie, based an a landmark 1940s comic book by Will Eisner, is still in the editing process when we speak but we are shown some generally baffling footage of Mendes as Saref to whet our appetites. Here, straight out of the shower and in a teeny towel, she is being arrested by lantern-jawed eponymous hero The Spirit (Gabriel Macht). “Hands behind your head!” orders Spirit. “Are you sure about that?” warns Saref, before lifting her hands up and, consequently, dropping her towel, Carry On style.

“But she's using her nudity as a weapon,” Mendes says. “And that's what I love about her. She literally uses everything she has in order to get ahead and to get what she wants!”

And before these words can sink in, and before you have a chance to wonder how they relate to Mendes herself and to the things that she has inevitably sacrificed to get ahead, her publicist, still smiling, looks at her watch and gives me a nod that says a whopping 17 minutes have now passed since I entered the room, and thus it's time to wrap this baby up.

We sort of bluster towards the finish line. Mendes, who is allegedly dating the film producer George Augusto, says that she's excited about playing the woman who seduces Keira Knightley's husband in Last Night (“It's really about how you define betrayal!”). She jokes about having buck teeth as a teenager (“I couldn't afford to get a retainer, and they're still buck now!” she says, shooting her upper jaw forward). And she says “No comment” to questions about Joaquin Phoenix's rumoured retirement (“He's a great friend. I can't say anything, but it's hilarious isn't it?”), and about her religious beliefs (“There are much more articulate people out there who can handle questions about God”). Finally, I wonder about her future. “What's left to do?!!” she yelps, taking mock umbrage, and making her publicist chuckle. “I've only just begun! I'm in my infancy here! This is just the tip of the iceberg!” She smiles to herself, and adds, “Yes, this is what your article should be called. ‘The Tip of the Iceberg!'”

And as we say goodbye, at minute 20, with kisses and hugs and promises to do it all again in another 18 months, I realise that she is right. That, thanks to the merciless efficiencies of the publicity industry, Eva Mendes the icon is now the visible tip of the iceberg. While Eva Mendes, the actress and the person, must remain below the surface, hidden from view, and tantalisingly out of reach.

The Spirit is released nationwide on January 1

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