Marchetto has at least woken up by the time we reach Galway, but he still looks like the living dead as he steps off the minibus. Within 90 minutes, though, he bounces on to the stage of the cavernous Black Box theatre to deliver a high-energy show that charms the punters into forgetting that they are slowly dying of frost-bite. Ennio Marchetto, the maestro of the quick change, has just effected his most dramatic transformation yet.
As I see him morph seamlessly from Lou Reed to M People to the Simpsons, and from Godzilla to Keith from The Prodigy to Judy Garland with just a few gentle tweaks of his paper costumes, all logic suggests that I am witnessing a triumph of artistic professionalism over fatigue. There is more to it than that, though. Even when he is not exhausted, Marchetto is hardly the life and soul off stage. He is shy and reserved, and prefers a book to conversation; he leaves any chattering to his long-term co- director and costume designer, Sosthen Hannekam.
But put Marchetto in one of his 140 costumes, and he seems to become another person. It is as if he can allow himself to access the wilder parts of his psyche only through inhabiting someone else's. His body changes from a rather homely figure into one that is graceful and balletic, and his lugubrious, rubbery face stretches into improbable shapes. If the producers of The Mask had cast Marchetto in Jim Carrey's role, they would have saved a fortune on computer graphics.
Marchetto was born in Venice, next door to Carlo Goldoni's house. As a teenager, he developed what might to many seem like conflicting passions, for commedia dell'arte and Walt Disney films, but he found a way of combining them by making elaborate costumes for the Venice carnival. After leaving school, he went to the Accademia dell'Arte and earned a few extra lire in his spare time working in his father's coffee-machine repair shop.
It was while he was dismantling an espresso machine that he got the idea for the show. "I daydreamed a paper Marilyn Monroe came flying from above," he says. "I locked the shop, pulled down the blinds and started lip-sync-ing to a record."
Most people would have taken such a fantasy as a sign they had been overdoing it a bit. Marchetto turned it into his life's work. He made himself a Marilyn costume, studied with Lindsay Kemp, toured his act around Europe and, in 1988, picked up first prize at a comedy festival in Bologna.
His career took off in earnest at the 1990 Edinburgh Festival, and since then, he has been on international permatour.
One of the keys to Marchetto's success is that his act can be enjoyed on a variety of levels. At its simplest, it is good clean fun - accessible to anyone from a child of five upwards. But it is also more than that. Marchetto is one of the new breed of post-clowns who draw on a variety of traditions, and he is keen to give credit where it is due.
"Italy has a history of impersonators," he says. "At the turn of the century there was one called Fregoli who was a hit across Europe. In many ways my act is a modern version of his, but commedia dell'arte is still the main inspiration - the costumes and masks make the characters."
Marchetto claims that his show is founded in innocence - that he is never nasty to any of the celebs he impersonates. Why he should say this is a mystery, as it is clearly untrue. Satire is close to the surface throughout the show, and is all the more cutting for its disguise. There is nothing worse than being savaged gently. Seeing Marchetto's Madonna gradually strip off more and more clothes until she is stark naked is a far more revealing exposition of the pop star's exhibitionism than any number of media meditations.
In many ways, Marchetto's characters choose themselves, as he concentrates on figures who are in the public eye and are instantly recognisable. He admits that this can cause problems. "I want to keep the show as topical as possible, but celebs come and go so quickly.
"I try to find something I like in all my characters, but so many people are artificially manufactured these days that it is sometimes almost impossible to find anything to relate to. The older stars, such as Barbra Streisand, are straightforward. Barbra is just Barbra. But take Celine Dion. It is so hard to see what she's really like, as everything about her, from her voice to her gestures, is so fake."
Given that Marchetto's Celine-turning-into-the-Titanic is one of the highlights of the show, can we take it, then, that he did eventually find something likeable in her? Marchetto pauses, before replying with an uncharacteristic bluntness. "No. But I like my Celine." And so will everyone else who sees her. Except Celine.
Ennio Marchetto is appearing at the Lyric Theatre, Hammersmith from Mon to 21 November. Box office: 0181-741 2311