I saw "The Yarn Car" in person in Houston about 12 years ago, it was an entry (and I think winner) in the annual "art car" show held there. It DOES have a late 60's look to it that's about the right era for the car. The guy who did it owned the Imperial, seemed to be what we would consider a "good owner" and was neat to talk to. While it IS covered in a WHOLE LOT of yarn, the Imp IS otherwise loved/respected as stock. The large/flat surfaces of the "slab-side" cars make great "palettes" for artwork like this, not that I'd condone this kind of thing on a widespread basis.
It made me think of the "I Dream of Jeannie" episode where the major's Pontiac convertible was given a psychedelic paint job by some hippies that befriended Jeannie.