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”.
His friend Troy taunted him while he wrestled the behemoth in the water.
As Troy helped him out of the water and into the boat, Munoz could tell that this was no ordinary catfish. Getting it into the boat was a whole different beast.
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.
"When I turned 13 and the famous Corvette Stingray came about, that car was pure sex and just an incredible machine. "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.
The 20-year-old Palestine resident caught a 55.5-pound blue catfish in Lake Palestine on June 8.
"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.
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Watching his friend pull catfish out of the water bare handed was enough to get Munoz to jump in.