If you do an internet search for "Moncton Benz", There are links for a twitter feed and a Facebook page, but the links are now broken. Also, Moncton Benz used to have a display of Mercedes vehicles at Champlain Place but this has not been present for some time.
I don't think I would get my hopes up over this one.....
Realistically, the NB market is probably only large enough for one dealership each for every luxury car brand. Saint John has Mercedes and Lexus, Moncton has BMW and Audi.
Probably the only way Moncton would get anything from Mercedes would likely be as a satellite of the Saint John dealership.