With its new platform, no longer a sibling to the Mustang.
Mercury Division, Ford Motor CompanyExcept for its final few years, the Mercury Cougar spent its life as a near-identical sibling to various Ford models. First it was a Mercurized version of the Mustang, then the Torino, then the LTD II (including four-door and wagon versions), then back to the Mustang again.
Then the Thunderbird got a new platform for the 1989 model year, complete with independent rear suspension, and the Cougar came along for the ride. Here’s a magazine advertisement for that Cougar.
Mercury Division, Ford Motor Company
If you bought the XR7 version in 1989, you could get it with a five-speed manual and a supercharger. The MN12’s suspension was so sophisticated that the Lincoln Mark VIII moved to it a few years later.
Keyword: 1989 Mercury Cougar Offers Pulse-Quickening Comfort