Steve McQueen's life in the fast lane on film

"When the film came out people perceived it to be such a bomb and everybody kind of blamed my dad because they knew that he was in control."

The film was Le Mans and the dad was Steve McQueen, and a new British documentary, which has screened at the Cannes Film Festival, tells the story of his vision of creating a pure motor racing film and the struggles he faced, not just in film terms but also in his personal life.

Released in 1970, the film continues to divide critics and fans. Some call it visionary filmmaking, the best racing movie ever made. But to others, it is a barely watchable movie with no dialogue for the first half hour.

McQueen's son Chad continues: "The thing has become such a cult classic, that we're talking about it 40-something years later and if a kid comes up to me at a race and says 'I loved Le Mans', that is exactly who my dad wanted to reach."

McQueen Snr died in 1980 at that age of 50 from a rare form of lung cancer.

In a poignant, never-before-heard clip of him talking just weeks before his death in Mexico - where he was receiving experimental treatment for the disease - he uses a racing analogy explaining that he has "just run out of gas".

The story of Le Mans begins with McQueen's long abiding love of motor racing, both as an avid fan and as a driver.

At that time, thanks to films including The Great Escape, The Thomas Crown Affair and Bullitt, Steve McQueen was the biggest movie star in the word with the box office and sex appeal of a combination of Brad Pitt and George Clooney.

His production company, Solar, had just signed a six picture deal to make the movies he wanted to make with himself in the starring role.

The movie McQueen wanted to make was Le Mans - based on the famous 24-hour race which takes place in annually in Le Mans, France.

As a committed driver, McQueen had a vision of making a film that would show people the beauty of his world and let people into the driver's seat if only for a brief time.

After the success of a rival and, according to McQueen, lesser film, Grand Prix - which starred James Garner, it was even more important to him to make a film free from special effects or artifice.

That meant filming real cars and real professional drivers, racing at real speeds, in real time, with a budget of $6m (around $37m today).

"He was a hugely powerful man at the time," says Steve McQueen: The Man and Le Mans director Gabriel Clarke.

"He was in place to make the ultimate racing film and yet because of that power, he unravelled so there's a real sense of a Shakespearian tragic hero. Which is at the heart of the story."

McQueen moved his entire production company to France to begin principal photography. He had a legendary filmmaker in John Sturges - who directed him in The Great Escape - but there was no script.

On top of the daily fights with Sturges over his refusal to make any concessions to a "Hollywood" style film, he was also in conflict with his wife Neile.

McQueen's reputation for infidelity was legendary and his appetite for casual sex was undiminished in France. His wife confessed to her own affair and the couple began to drift apart.

As a 10-year-old on set, Chad McQueen was sheltered from the worst of it.

"As a father myself, you never want to expose your kids to that kind of stuff and he didn't. I'd see my parents fight every once in a while but until I was older, I never released the depth of the infidelity."

Co-director and producer John McKenna said approaching the McQueen family about such a fraught period had been a difficult task.

"We knew that it would be a tough conversation to have, to persuade Chad about this film about a difficult time in his life.

"There were going to be people who were going to say things about his father that maybe he hadn't heard before or didn't like hearing or wasn't keen on the rest of the world hearing."

Sturges eventually walked after six weeks of filming, grandly stating: "I'm too old and too rich" to put up with it. He and McQueen would never work together again.

The constant battle with his film company took its toll on McQueen and, with the production running over budget, he was forced to sign away full creative control of the film.

It resulted in a rift between McQueen and some of his closest friends and business partners.

The filmmakers had access to hours of rare footage from the film, plus archive interviews and McQueen's behind-the-scenes written correspondence.

Clarke says: "He comes across as obsessive, a perfectionist who wanted total control ...and as somebody who was prepared at this time to sacrifice a great deal for one film. You can like him or dislike him for that."

The film was eventually released towards the end of 1970 after a gruelling seven-month shoot.

McQueen didn't even bother going to the premiere and he never raced in a car again.

Changes to the film industry over the last 40 years mean there is little chance a studio would give an actor a high budget to make what is effectively an art house film with a very specific audience in mind.

That and the very real danger that he could be injured or even killed making it. Tragically, one of the British drivers involved in the film lost his foot and lower leg after a horror crash.

Now 35 years after his death, McQueen remain an icon of cinema. He was nicknamed the King of Cool in the 1960s and little has happened to change that perception of the actor.

"If I could figure out why, then I would bottle it," admits Chad McQueen. "It's cool and my daughters friends will come up to me and say they just watched Bullitt for the first time. Wow. It's cool."