Edward Smith, who lives with his current "girlfriend" – a white Volkswagen Beetle named Vanilla, insisted that he was not "sick" and had no desire to change his ways.

"I appreciate beauty and I go a little bit beyond appreciating the beauty of a car only to the point of what I feel is an expression of love," he said.

"Maybe I'm a little bit off the wall but when I see movies like Herbie and Knight Rider, where cars become loveable, huggable characters it's just wonderful.

"I'm a romantic. I write poetry about cars, I sing to them and talk to them just like a girlfriend. I know what's in my heart and I have no desire to change."

He added: "I'm not sick and I don't want to hurt anyone, cars are just my preference."

Mr Smith, 57, first had sex with a car at the age of 15, and claims he has never been attracted to women or men.

But his wandering eye has spread beyond cars to other vehicles. He says that his most intense sexual experience was "making love" to the helicopter from 1980s TV hit Airwolf.

As well as Vanilla, he regularly spends time with his other vehicles – a 1973 Opal GT, named Cinnamon, and 1993 Ford Ranger Splash, named Ginger.

Before Vanilla, he had a five-year relationship with Victoria, a 1969 VW Beetle he bought from a family of Jehovah's Witnesses.

But he confesses that many of the cars he has had sex with have belonged to strangers or car showrooms.

His last relationship with a woman was 12 years ago - and he could not bring himself to consummate it, although he did have sex with girls in his younger days.

Mr Smith, from Washington state in the US, kept quiet about his secret fetish for years, but agreed to be interviewed as part of a channel Five documentary into “mechaphilia”. He is shown meeting other enthusiasts at a rally in California

Talking about how his unusual passion developed, Mr Smith said: "It's something that grew as a part of me when I was a kid and I could not shake it.

"I just loved cute cars right from the beginning, but over the years it got stronger once I got into my teenage years and was my first having sexual urges.

"When I turned 13 and the famous Corvette Stingray came about, that car was pure sex and just an incredible machine. I wanted it.

"I didn't fully understand it myself except that I know I'm not hurting anyone and I do not intend to."

He added: "There are moments way out in the middle of nowhere when I see a little car parked and I swear it needs loving.

"There have been certain cars that attracted me and I would wait until night time, creep up to them and just hug and kiss them.

"As far as women go, they never really interested me much. And I'm not gay.”

Mr Smith is now part of a global community of more than 500 “car lovers” brought together by internet forums.