MPG with Arduino Bluetooth

In fact - I do not know a ready solution for your task.
If you know how to program microcontrollers - then you should go this way:

  1. Establish a bluetooth connection.
  2. Use hardware interrupts to determine the frequency, with any interval, to obtain discrete values.
  3. Transmit values by bluetooth.
  4. Go to 2.

If you want me to do this for you - PM me