It's been an uneven lesson.
Mercury had the Capri in the past, when Ford didn't. I get your point, but at present:
Ford - 18 vehicles at
http://www.ford.com/...le-showroom#/ford:
F150, Flex, Focus, Focus Coupe, Fusion, Fusion Hybrid, Mustang, Taurus X, Taurus, Edge, Escape, Escape Hybrid, Explorer, Explorer Sport Trac, Expedition, Ranger, F250-F350-F450, E-Series
Mercury - 7 vehicles at
http://www.ford.com/...showroom#/mercury:
Mariner, Mariner Hybrid, Mountaineer, Grand Marquis (no de Sade Edition, though), Sable, Milan, Milan Hybrid.
Yes, there's some overlap, and maybe more than there should be, but not as much as there is among GM divisions: Chevy (17), Pontiac (9), Buick (3), GMC (16), Saturn (5), Hummer (6), Saab (6), Cadillac (12). There's a
lot of overlap there, especially among the SUVs/Crossovers (where the US companies put their development dollars over the last decade or so).
I think GM's most obvious waypoint on the way to C11 was when they decided to shift V-8 engines among divisions. What made a Pontiac a Pontiac, and an Olds an Olds, was ultimately the engines. Sure, they could have economized by sharing more parts, but when they put Chevy engines in Oldsmobiles with no benefit for the buyer, it was a sign that GM was killing their brands.
Cheers,
Scott.