When in a helicopter/plane/tank, vehicle's position is always shown on the map, even with "show friendlies" disabled and in a vehicle without a GPS.
It would be nice if this "localisation" were related to the vehicle being equipped with a GPS or not, based on a difficulty setting (or not?).
See this wonderful artwork by an eminent member of this Splendid™ community:
"CfgInGameUI" >> "Cursor" >> "mission"