went downhill in the 80s and BMW and Mercedes took off?
It could be argued, and I have many times, that it was because Chevy bumped up the FWD chevy models to replace the RWD models and all the luxury buyers went to RWD.
Cadillac didn't make a resurgence until the RWD CTS came on scene...
The Challenger/Charger/300C also breathed new life into Dodge's car lineup, and it was primarily the RWD drivetrain that did it.