After shadowing prolific designer Karl Lagerfeld for two years while producing Lagerfeld Confidential, the candid documentary that was released last autumn, its director, Rodolphe Marconi, confessed: “Suddenly, well, everything just seemed so boring!” Perhaps as a result the 32-year-old award-winning French filmmaker embarked on a new project, allowing him to become intimately acquainted with the one fashion legend who could trump Lagerfeld’s talents: Gabrielle “Coco” Chanel.

Until now, details of the biopic, which Marconi wrote and will direct as of January 2009, have remained top secret, but the project is likely to generate buzz as the Cannes Film Festival kicks off later this week. Budgeted at €50,000m ($77,000) and backed by Christian Fechner , it will star Vanessa Paradis. “I hope Karl will have time to make the costumes,” says Marconi of his cinematic extravaganza.

It is but the first of a group of Chanel biopics, however, which generated the sceptical Variety headline “Crowded Runway” this time last year. They include a feature set to star Audrey Tautou; one by 1970s maverick William Friedkin; and another by writer-director Danièlle Thompson, famed for her work on the César award-winning romance Avenue Montaigne.

Meanwhile, Chanel is among a number of fashion legends to have captured filmmakers’ imaginations. Pending release, for example, is Emmy award-winning filmmaker RJ Cutler’s documentary about Anna Wintour, US Vogue’s powerful editor-in-chief, as she masterminds an all-important September issue of her magazine, as well as Valentino: The Last Emperor, by Vanity Fair special correspondent Matt Tyrnauer.

Meanwhile, Douglas Keeve, the documentarist behind Unzipped, the hit 1995 portrait of designer Isaac Mizrahi, as well as Hotel Gramercy Park, which just debuted at the Tribeca Film Festival, is now turning his attention to the “Polly Mellon project.” For two years, Keeve filmed the exuberant former Allure magazine creative director and one-time Diana Vreeland protégé and recorded her phone calls. Finally, there is the as yet untitled Ridley Scott epic set to chart the “wild, glamorous” and macabre Gucci dynasty, complete with the 1995 assassination of Maurizio Gucci.

The film industry pursues trends just like the fashion industry and, it seems, fashion is cinema’s of-the-moment genre. What makes this interesting is it is an historic anomaly: after all, luxury goods may appeal to the masses but even recognised fashion names rarely shift popcorn.

“The track record for films about fashion, especially documentaries, is decidedly mixed,” noted a January 2008 Variety report. Even a film cited as an exception, Yves Saint Laurent: His Life and Times, grossed a paltry $99,819 after its 2004 release. Correspondingly, it has been difficult for directors to get funding for such projects, contributing to their rarity.

“Nobody believed in it,” says Marconi of his struggle to garner Lagerfeld Confidential’s €800,000 budget, for example. Similarly, though two of the four fashion documentaries recently made by French journalist Loïc Prigent, Signé Chanel and Marc Jacobs & Louis Vuitton, have sold globally and transferred to DVD, the majority of television executives to whom Prigent appeals for backing “don’t get the point, because the treatment of fashion on television has been dull and conservative for so long. And it is a macho thing. For example, a “Victoria’s Secret” documentary would get the green light quickly.”

According to Douglas Keeve, director of Unzipped, his job remains “hard” because of the plethora of reality fashion shows currently dominating the television airwaves.

“While reality television has given documentaries a commercial viability, they have also flooded the marketplace. Old school documentaries, which is what I do, and which are more authentic or ‘real’ than reality television [which is mostly scripted], are still a tough sell.”

And even once funding is secured, the going can be rough out in the field. Because fashion folklore, or the mythology associated with venerable brands, is crucial to the marketing of their expensive merchandise, in-house PR teams are extremely protective about providing the unlimited access on which these films rely.

“Terrifying,” Prigent recalls of an initial meeting with an apprehensive Marc Jacobs. Vuitton’s creative director had agreed to make himself and his domain completely open to Prigent and Dominique Miceli, his producer.

“But two days before, Marc had quit smoking, so he was anxious and angry,” he continues. “Everything was ‘no!’” Tensions eased once the crew and Jacobs decamped from Vuitton’s Paris atelier to a splashy Tokyo fashion event. “Marc had started smoking again,” says Prigent, “so then it was all ‘yes.’”

Then there is the inevitable inertia generated by luxury brands’ insistence on the “final cut”. “I thought he’d cut the part [displaying] him without his sunglasses, but he said it was OK,” says Marconi of Karl Lagerfeld’s reaction to his cinematic self-portrait, for example.

So why are so many directors willing to endure so much in order to make a “fashion film”?

Not because the executive view may change as fashion continues to generate billions, or that the phenomenon of 2006’s The Devil Wears Prada, which grossed a staggering $300m, has induced fashion filmmakers to pursue their art in the hope of a comparably huge payoff. But, rather, these directors recognise the potential of the fashion industry as entertainment. As all of them point out, a “fashion film” does not, in fact, come close to describing the truth of the genre.

It’s “so much more” insists a Fox 2000 spokesperson of the Gucci feature, currently being scripted by Charles Randolph, author of Sydney Pollack’s 2005 thriller The Interpreter.

For Marconi, it was Lagerfeld’s “genius” that attracted him to the documentary, not his mega-rich lifestyle or starry entourage, while for Tyrnauer, it was the “love story” that ensued after Valentino Garavani met Giancarlo Giammetti on Rome’s Via Veneto in 1959 and, entrusting his business affairs to the former architecture student, together they built the Valentino SpA luxury brand. Though the director allows his $1m “verité” film does capture Valentino’s “truly magnificent lifestyle”, Tyrnauer insists his movie goes beyond the “luxury and fabulousness” endemic to Valentino’s rarefied world, portraying “a deeper human story”.

“It is a marriage but more than a marriage,” he reflects of Valentino and Giammetti’s interdependence. “It is a unique phenomenon – a love in all its strange permutations.”

In other words, the gorgeous and superficial context of fashion has revealed, underneath it all, a treasure trove of subtext.

Bronwyn Cosgrave is the author of ‘Made for Each Other: Fashion and the Academy Awards’.