I thought I've seen about everything Cadillac
This has more '63 than '64 styling cues. The 2 years are often confused.
I believe this car started off as a 4dr.Sedan DeVille. The front doors are welded shut, and the rear doors have become the only doors...assuming the whole thing isn't some fiberglass contraption.
The rear wheel arches are Eldorado like for the year as knightfan suggested.
There's something funny about this pic. Maybe a clay model?
Something about it says it's not a real car.
Look behind the front wheel into the wheel tub. If this were a real operable automobile, you wouldn't be able to see all the way through the wheel tub to the other side.
That's all I got.