I just replaced battery, sparks and coils and I am wondering if the battery replace has any effect on the electronics of RX8, apart from loss of radio stations and the clock reset.

In particular, I am concerned in the new software upgrade that the dealer installed. Is that lost when you disconnect the battery? I noticed that the idling of my car changed right after this, and that was indeed improved right after the software upgrade, which makes me think that the car came back to the initial state with the old software.

 

No, it would not lose the latest flash, it is stored in non-volatile memory.

The idle etc. may change because you might lose the fuel trim settings until you run a few drive cycles to reset them.

S