The Crown Victoria continued the six-window treatment found on the successful 1986 Ford Taurus, whereas the Grand Marquis had a four-window passenger compartment greenhouse.
In 1992 the base price for both cars was around $3800, even though Mercury was traditionally a more upscale brand than Ford. And the models sold at around the same levels prior to their 1998 facelifts. When preparations were made for the facelifts, Crown Victorias were given Grand Marquis 4-window greenhouses. Post-facelift, Grand Marquis' consistently outsold Crown Victorias.
The only conclusion I can draw, lacking much information beyond the production numbers cited in the first two links above, is that Ford's economy move to reduce styling differences for production efficiencies likely disenchanted potential buyers who preferred a 6-window configuration.
For what little it's worth, I like the 4-widow design better than the 6-window version.
The redesigned Crown Victoria. A cue carried over from the initial Taurus design is the "floating" Ford Blue Oval on the car's front. Another, of course, is the six-window greenhouse.
The four-window facelifted version. The front features a new, prominent grille, and larger light assemblies.
It's hard to see in this photo, but the side sculpting between the wheel openings seems unchanged. Besides the greenhouse changes, the main differences are at the front and rear. Lengths are essentially identical.
The trunk lid and rear fender form curves slightly downwards while the tail light assemblies echo the framing of the frontal light assemblies.
The trunk profile is raised and taillight assemblies feature a different theme while the license plate has moved from the bumper to the trunk lid..
The equivalent Mercury has essentially the same tail lights. Side sculpting is simpler.
The original 4-window Grand Marquis styling. Rear sculpting and tail lights are similar to the contemporary Crown Victoria.
