Madness in his method - Emile Hirsch interview

Emile Hirsch, star of the Wachowski brothers' new flick, Speed Racer, is happy to put himself through major discomfort in the name of art, finds James Mottram

THERE'S something very masochistic about Emile Hirsch. For his last film, Sean Penn's Into The Wild, the 23-year-old lost nearly three stone to play real-life adventure-seeker Christopher McCandless. So dramatic was his weight loss that he began to hallucinate. "One time I woke up and thought I was still on the Grand Canyon on the Colorado River," he says. "I thought the crew had abandoned me. I woke up and went: 'Hello, hello!' and for 30 seconds, I crawled forward and thought I was on the river bank. Then I realised I was at the very edge of my bed and all the lights were off in the motel room."

The only genuine madness was that Hirsch was overlooked at this year's Oscars for his stupendous turn. Not one to sulk about this, he also refused to rest on his laurels. "After Into The Wild, there was no physical thing I could do to match that," he says. "So it became a mental thing – 'How much can you imagine? How much can you take?'" It arrived in the shape of summer behemoth Speed Racer. The new film from the Wachowski brothers, the duo behind The Matrix, was just as testing as Penn's film in its own way. "I was laughing a little bit, going: 'Man, I certainly don't make it easy on myself.' But that's part of the fun for me – pushing myself to different extremities."

While the evidence of this was on screen with Into The Wild, it's less obvious in Speed Racer. It's based on the Sixties Japanese cartoon, and Hirsch plays the title role – a young man who gets his kicks from high-speed racing in a futuristic world and takes on a corrupt racing car corporation. With the bulk of the film's backdrops shot against 'green-screen' and added in by computer later on, Hirsch was often on his own in a 'gimble', a machine that simulates the movement of his car. "You're basically locked in a chamber by yourself and it can shake you really violently, giving you borderline whiplash," he says. "I spent 20 days alone in this thing. It was like solitary confinement."

Hirsch deserves praise for his performance, if only for finding new ways to grimace and groan as he pretends his face is struck by g-forces. Like a psychedelic cross between Wacky Races and The Jetsons, this colourful blockbuster is not exactly an actor's piece (despite Susan Sarandon and John Goodman putting in appearances as Speed's parents). Yet Hirsch says the strain of acting opposite nothing was frustrating. "I felt close to breaking point. You're wondering: 'How am I going to avoid saying this is enough and just walking off?' It's an exciting place to be, though. You're never bored."

As a fan of The Matrix, Hirsch's chief reason for making Speed Racer was collaborating with the elusive Wachowski brothers. Full of praise for them (they're "from another planet", he says), he also enjoys the fact that they refuse to do any interviews or promote their movies. "It's so cool that there are these really trippy movies that they make, and the mystique just builds. How many directors these days get to be a mystery to people? How much cooler was Oz than seeing the little dude behind the curtain?"

Sitting in an upmarket London hotel, Hirsch is more talkative than when I last met him. Maybe it's the pure adrenaline of promoting a film such as Speed Racer. When we met for Into The Wild, he was lying on a sofa, barely mustering the energy to speak in his soporific Californian drawl. Still, despite a 13-year career, that was the first time he'd ever really had to do press and it was as much of an endurance test for him as the film itself. Previously, he'd flown under the radar – playing a vicious thug in Alpha Dog, a skateboarder in Lords Of Dogtown and a straight-A student in studio comedy The Girl Next Door. Even in the pretentious drama The Air I Breathe – receiving a belated release one week after Speed Racer – Hirsch buried himself in an ensemble cast.

While smartly aligning himself with experienced actors such as Sigourney Weaver (Imaginary Heroes) and Jodie Foster (The Dangerous Lives Of Altar Boys), part of the reason Hirsch has, until Into The Wild, sailed through Hollywood relatively unnoticed is that he's refused to sell himself as a studio pin-up. Despite his good looks and being born and raised in LA, it's never come naturally to him. When he began going for auditions, he never got hired for commercials. "You have to do the 'cutesy performing thing'. I couldn't summon the inner performer to smile on cue. I'm not interested in that."

With Hirsch's father, a producer, and his artist mother going some way to explain his theatrical leanings, Hirsch notes it was his older sister who first inspired him. "She loved singing and performing, and I took after her in a lot of ways. I just tagged along for the ride."

Even now, he balks at being seen as this season's hot actor. "I don't really like the slogan 'It boy'," he says. Is he ready for his life of relative anonymity to be turned upside down by Speed Racer? "I'm not," he says. "But it's a by-product of making the films I've wanted to make."

Hirsch appears pro-active when it comes to his career. "I'm not a ball in a pinball machine. I know what I want," he says. Case in point: he's just completed Gus Van Sant's Milk. A long-gestating story about Harvey Milk, a San Francisco supervisor who became the first openly gay elected official before he was murdered, it reunites Hirsch with Penn, who plays the title role. It's another intense role for Hirsch as Cleve Jones, a gay rights activist who worked for Milk on his campaigns. "He was a very extreme activist back when he was younger. He's very forward and very aggressive, more masculine than effeminate." Referring to the late Heath Ledger in Brokeback Mountain, he says: "I think Heath changed the way the public thinks of gay characters in movies."

While Hirsch has not ruled out the prospect of returning for some more green-screen hell in a sequel to Speed Racer, his next challenge, he says, is to do a play, another "intimidating" prospect. "Artistic ambition is important," he says. "And it seems it would be a great time to do some theatre, like a new extreme."

• Speed Racer opens on Friday. The Air I Breathe opens on May 16