The BMW Motorrad Navigator V has PCB P/N of 105-2052-00 which indicates it's different hardware from both zumo 590 and 595 which share PCB P/N of 105-02341-00. Non-identical boards mean you can't cross-flash whereas it may be possible with identical boards. [Only registered and activated users can see links. ].
Interestingly, BMW_Motorrad Nav IV is not only identical hardware to zumo660 as they share PCB P/N 105-1452-00 but also HWID of 0924 and accordingly they even use the same firmware.