Even though they depict 1958 Edsels, some of these pictures were actually made in 1955 & 1956.  Note the '57 Mercury roofs on the C-C models and the unusual pickles on the Citation.  The wagon is particularly interesting since it's a Bermuda on one side and a Roundup on the other, a three-door!  This car is actually a full-sized clay & fiberglass mock-up.  The disguised Citation convertible was photographed at the Ford test track in Dearborn.  Notice the backup deletes.  There's a view of the rear quarter of one of these test mules taken inside a large building.  Look closely and you'll see that the Edsel taillights have been replaced with substitutes.  This car was probably tested on public roads.  Phil Skinner has uncovered interesting information at the Ford Archives concerning all of these '58 prototypes and pilot cars.  He found memoranda regarding the cars with '57 Mercury roofs, for example.  They were later fitted with '58 roofs.  (Yet one still found its way into the '58 prestige catalog.)
Click images to enlarge.