Well ,this thread reminded me my "lost in post"
diagnose tool,a year ago and decided me to get something...at the end. Looking on internet I bought an interface ELM 327 OBDII and a cable adapter from 20 pin BMW to 16 pin OBD.
The interface uses my android phone with OBD Car Doctor or Torque, through Bluetooth (which is very comfortable either).
The interface works for 96 to nowadays all vehicles (brands) having OBDII socket.
With BMW is using protocol ISO 9141-2.
Very happy !
It costed me only 13 EUR! Its weight is 34g and is not bigger than a matchbox. You can keep it in the OBD socket while your phone can display, in real time, many infos not present on the dashboard.