The strikingly sleek Chevy Nomad brought mid-century modern design to the utilitarian station wagon. The Nomad got its name, along with its unique roofline and rear body treatment, from a 1954 GM Motorama Corvette concept wagon conjured up by GM design chief Harley Earl – father, as well, of the 1953 Corvette roadster.
For the 1958 model year, Chevrolet moved the Nomad name to its top-line four-door Bel Air based station wagon, right above the new mid-priced Biscayne based Brookwood. This was the only four-door Bel Air based Nomad station wagon. The new Nomad featured body-on-frame construction, using the "X" frame used on other 1958 to 1964 Chevys, as well as Cadillac.
Sources: Chevrolet; Wikipedia, 2012