Originally Posted by exdos
The device is not a toy but a serious bit of equipment that also reads fault codes, so for me is a sound investment.
Using high quality accelerometers to infer torque output does not mean that you are dealing with a toy. If you are referring to the iPhone software that is on the market, that’s not what I am referring to, but that is not a high precision setup. Use a high precision setup and you'll have solid data. So, you need to tone down the language and attitude here.
Using vehicle speed data and processing it in conjunction with rpm data can yield relevant outcomes if the vehicle model that is being used is comprehensive and valid.
Is the tool you are using specific to BMWs? If it is a general OBDII tool, it shouldn't let you read/interpret BMW specific codes.