When the next great extinction comes, the aliens will come down to preserve the highest species. They will make some quick observations and assume that the automobile is the dominant species on Earth. They'll pick them up and preserve them for a few million years or so until the Earth settles down again. During this time, they will work on elevating the species to intelligence and rewire them with reproductive capacities. They will then return these intelligent automobiles to Earth to reseed it with higher forms of life.

The movie "Cars" isn't a fantasy, it's a depiction of life on earth two million centuries from now.