Are you sure it wasn't a Lincoln Continental? They have a similar look to the Imperial, and were manufactured with suicide rear doors. I don't recall any Imperial models with suicide doors as an option. All the pictures I can find with four-door Imperials all show normal doors.
I know it was a Chrysler Imperial. Maybe I am confused about the suicide doors.
It looked similar to the car in the movie “Animal House”. Maybe that it where I remembered the suicide doors from.
It was 40 some years ago. Holy Crap!