Air Inter ordered 10 examples of a stretched version with reduced fuel capacity for its generally very short ranged network.
Since the program ended with that, then the shorter, lower capacity prototype was later rebuilt to the same standard and sold cheaply to Air Inter.
That's the background behind dozens of threads here at a.net bashing the Mercure for it's short range.
If the Mercure had sold in numbers to ordinary airlines, then the bulk would have been the original shorter version which would have had the same lower seating capacity and longer range capability as the B737-200.
The truth is that the Mercure came too late into an already overcrowded market dominated by BAC One-Eleven, DC-9, B737 and to some extent Trident and B727.
Happy landing, Preben Norholm
Always keep your number of landings equal to your number of take-offs