According to Hoovie, some manufacturers call sedans coupes because they have coupe rooflines in the rear, which he does not appreciate, because he has a head, and cannot simply set it in his lap (my words). He also found Mercedes claiming that the Society of Automotive Engineers defined coupes and sedans not by the number of doors, but by interior volume, which would make small four-door cars coupes and large two-door cars sedans. He also gave examples of various cars that had their own terms like fastback, sportback, freckleback, wait, no...