The Cougar was Mercury's entry into the late '60's pony-car battle. The 1967 Cougar was based on that year's Mustang, but with a 3-inch longer wheelbase and totally different sheet metal (although I suspect the glass and maybe the roof were shared).
The '67 and '68 models were nearly identical, and represent, in my view. one of the most beautiful automobile designs to ever come out of Detroit. The bodies were very 'sculptured' and there's not a bad line anywhere on the car. I suppose that's what is meant by a 'classic' design: It's been 40 years since the '67 Cougar was introduced and the design still seems fresh and appealing.
The Cougar was moderately restyled for 1969, but it wasn't as elegant as it had been. The sculpted body lines were gone and the 'flat' sheetmetal just didn't look distinctive anymore.
Cougars would continue to be based on the Mustang platform through the '73 model year, but as the years went buy the car got bigger, and more aggressive-looking, and never returned to the 'elegant' appearance of '67-'68.
In 1974, the Cougar was separated from the Mustang, and my interest in the car stops there. I will, however, highlight the evolution of the brand from 1974 to 2002 as it was seemingly an orphan looking for a home.
1974 was the year the Mustang "shrank" and became the Mustang II, and the Cougar was shifted over to the larger Torino platform for '74-'77, and then the Ford LTD II platform for '78-'80.
In '1981, the Cougar was shifted back to a smaller platform based on the Ford Fairlane/Mercury Zephyr car line. The folks at Ford were so inept at marketing this car they even had a station wagon version in '82. The most gorgeous of all the pony cars in '67 & '68 was now being offered with a station wagon version. And the knuckleheads in Dearborn sat in their plush chairs, behind their executive desks, staring out their vast windows, wondering, "Where have our customers gone?"
The Cougar grew again in 1983, based on the new, areodynamic Ford Thunderbird platform. It would stay tied to the Thuunderbird through the 1997 model year when Ford pulled the plug on the T-bird.
The Cougar name was resurrected once again in 1999 by putting it on the Ford Contour/Mercury Mystique 4-dr sedan platform. In all fairness, that platform did have a 2-dr version in Europe, but how many times can you change the soul of a car before the buying public has no connection with the brand whatsoever? Ford killed it for good after the 2002 model year.
Updated February 26, 2020