Cadillac's official spelling went back and forth from year to year, and in some cases on the same page of a brochure; I don't think we should do the same. Night_cub went through the brochures and claims 1968 as the year the brochures started to spell it as one word, but it's not very consistent. Personally I'm fine one or the other, but I don't think the name should alternate between de Ville and DeVille on the basis of what might very well be a typo.