For petrol there's two that spring to mind, the Miller WAR chip from the states and Megasquirt. I was looking into these with running LPG on the shed and wanted rid of the restrictive mixer plate.
Was looking for something similar to RICA for Volvos or Hondata. Its for a Bravo 1.2, bosch ecu, eobd2 ( earlier type so no can interface or eobd 16pin plug)
The plan is when funds permit to get an aftermarket ecu and use at least 3 different maps
The standard map
An economy map
A pants on fire map
The megasquirt would take a lot of effort to implement but would be worth it. Was looking at the WAR chip, Is it meant specifically for BMWs?