'Struth - it's more common than you might think!
As stated in the theme song for 'My Mother The Car', apparently everybody in Toobworld knows that we are all reincarnated eventualy. And in the show, again according to the song, Dave Crabtree's mother made the choice to come back as the 1928 Porter instead of as another human being or even as an animal like a dog, or an organ grinder's monkey, or even as a bowl of petunias (all of which have been reincarnated humans in one TV outlet or another).
This same voluntary decision to become a car must have been made by the vengeful spirit who possessed Oliver Pope's car in "You Drive", an episode of 'The Twilight Zone'. Pope had struck a boy with the car and fled the scene. Afterwards his car came alive in order to force him into owning up to his crime.
It's unclear as to who that spirit might have been - it's certainly not the boy as he was not yet dead. Maybe it was the soul of one of the boy's deceased relatives. Or perhaps it was the soul of a children's welfare advocate; maybe somebody who once worked with Neil Brock. ('East Side/West Side')
Another vengeful spirit operating heavy machinery might have been "Killdozer". But it's believed that an alien being was actually at the controls in some way.
Whether the relentless truck in "Duel" was possessed or controlled by aliens or just manually operated by a human being was never resolved. We never got a really good look inside the cab of that truck. But at the same time, I don't think it was ever a consideration to be anything else than just a mad trucker behind the wheel. Things were less complicated back in the early 1970s.....
KITT of 'Knight Rider' would not fall into this category. It's neural net, probably based on the cybernetic designs of Questor and Hymie the Robot, mirrored an actual personality.
Over in the Tooniverse, auto-reincarnation could be the splainin for 'Speed Buggy'. And 'Turbo-Teen' was a true interface between car and man - an 'Automan', if you'll forgive me for mentioning that.
(In the 'Futurama' episode "The Honking", the robot Bender transformed into a were-car at night.)
As for the 'Supernatural' truck in "Route 666", it was the evil, murderous soul of young Cyrus Dorian, a racist who had been killed in the early 1960s. But as Dorian had murdered several people while he was alive, his monster truck rally of retribution only staved off the inevitable - a one way ticket to Hell.
Toobnote: It's possible that the family name of "Dorian" was handed down as a first name to a cousin so as to reinforce the familial link to a new generation.
And thus Dorian Lord of 'One Life To Live' might provide a "family tie" to 'Supernatural'.....
Everybody knows in a second life, we all come back sooner or later.
As anything from a pussycat to a man eating alligator.
Well you all may think my story, is more fiction than it's fact.
But believe it or not my mother dear decided she'd come back.
As a car...
As a car...
She's my very own guiding star.
A 1928 Porter. That's my mother dear.
'Cause she helps me through everything I do
And I'm so glad she's near.
My Mother the Car.
My Mother the Car.
My Mother the car.
'My Mother The Car'