But the brand failed due to several reasons, some of which I wrote about, along with others mentioned in the first link.
The 1958 Edsel line was comprised of four models. In ascending price order, they were Ranger, Pacer, Corsair and Citation. The first two were based on Ford bodies, the rest on Mercury bodies. Fords and Mercurys were redesigned for the 1957 model year, and I'm using those as the basis for the discussion below, rather than facelifted 1958 models.
Setting the scene, entry-level Ford Customs had 116-inch (2946 mm) wheelbases, and Ford Fairlanes had wheelbases of 118 inches (2997 mm). All '57 Mercury wheelbases were 122 inches (3099 mm). Edsel Ranger and Pacer wheelbases were 118 inches, like those on Ford Fairlanes and Fairlane 500s. Edsel Corsairs and Citations had the longest wheelbases, 124 inches (3150 mm). As will be seen below, wheelbase differences were dealt with fairly easily because the cars were built body-on-frame, rather than using unitized bodies that are today's norm.
Unless noted, images below are of cars listed for sale.
1957 Ford Custom 300 Fordor Sedan
First, the entry-level Ford 4-door sedan on the short wheelbase.
1957 Ford Fairlane Town Sedan - unknown photo source
Ford's longer-wheelbase 4-door sedan. Rear door widths provide the clue for lengthening. The Fairlane door is wider, and the passenger compartment top lengthened to accommodate that, while the shape of the backlight window was unchanged.
1958 Edsel Ranger 4-door sedan - Mecum Auction photo
This is the Edsel based on the car above. Wheelbases are the same, so the basic structures are the same as well and visual differences are due to cladding.
1957 Ford Fairlane 500 Town Victoria - factory image
Here is Ford's '57 4-door hardtop sedan.
1958 Edsel Pacer 4-door hardtop
And an Edsel version using the same structure and wheelbase.
1957 Ford Fairlane Town Sedan
Repeated photo. Compare to the Mercury 4-door sedan below with its 4-inch (102 mm) longer wheelbase.
1957 Mercury Monterey 4-door sedan
The Mercury body is different, though there are a few intriguing similarities. Compare the door cutlines. They are virtually the same (the photo of the Fairlane 500 4-door hardtop shows the lines more clearly), the forward Mercury cutline being more vertical, and rear door aft cut shaping differing around the wheel opening. Windshields are essentially the same, though framing is more angular on Mercurys. This suggests possible structural carryover to an otherwise different platform. Otherwise, passenger compartment tops differ along with body sheetmetal cladding. But I could well be wrong: an experienced body shop crew would probably know the truth. Anyway, for styling analysis purposes, we can regard Mercurys as having distinct body designs.
1957 Mercury Montclair 4-door hardtop - via Curbside Classic
Edsel Corsairs and Citations were hardtops or convertibles, so compare this Mercury 4-door hardtop to the sedan above. The main difference is that the hardtop has a wider C-pillar.
1958 Edsel Citation 4-door hardtop - unknown photo source
The main structural difference is the backlight window shape and framing along with slight aft side window reshaping and a thinner C-pillar.