I think that was a key question answered. the “operating system” I surmise, lives in the program memory. In most microcontrollers, this is protected by security bits. It cannot be downloaded or reflashed. Even a few lines of code different will likely make a clk ecu uninterchangeable to an slk even when running exactly the same engine. Thats the deal breaker. From what you say it seems we can only reflash the 512KB internal eeprom which seems to be logical. The whole map file can fit in 512KB? As I said I wasn't sure and thank you for the answer. 512KB can be a lot of data if its pure numbers.But Maps do not contain the operating system which calculates and manipulates that data and thus controls events via components !!
As for different hardware, I was thinking that GHIS4u would add the missing components. As long as the PCB is the same, this is not an impossible task. Most manufacturers will use the same base design and remove unwanted components (mostly for reliability and ease of testing) to fit other appliances.