Inappropriate coolants in an all-aluminum engine (well, mostly aluminum) could be problematic. I would stick with smart's recommendations. M-B themselves specify the following (M-B Sheet 325.0):
Mobil Permazone Antifreeze/Coolant
Mobil Permazone 50/50 Prediluted
Old World Industries EURO Peak Coolant/Antifreeze
Valvoline/Zerex G05
Valvoline/Zerex G48
BASF Glysantin G05
Just as M-B 229.5 (engine oils) is included in smart's shop info, I would bet that M-B 325.0 is also. What are engine-maker Mitsu's recommendations? Dunno.