I have a RaceCapture Pro/mk2 and using the bluetooth module to connect to an Android phone (HTC Evo 4G LTE running Android 4.1.1). The phone does not have cell service enabled (it's my old Sprint phone and I'm no longer with Sprint).
It seems to work okay except when I shut my car off before exiting the app... Trying to exit the app after the RCP is switched off just hangs and eventually gives a prompt that the app has stopped working.
The RCP is tied to the engine switch and so it turns off (loses power) when I turn off my engine. Although I can put another switch in for the box, there is a kill switch for the car and so it will always be possible to switch off power to the box (and the entire car).
It also seems to have trouble re-acquiring the box after connecting and losing the connection (for example, when I drive to the grid and switch off the engine/box at the grid).