Originally Posted by wpoll

Or then there's this..

https://www.car-solution.de/produkt/...er-e38-x5-e53/

Translation of the German text is: -

With this module, you can call up the following information by pressing and holding the BC button on the turn signal lever:

- Display of the oil temperature

- Display of the cooling water temperature

- Display of the battery voltage

- Digital speed display

No additional sensor or sensor is required, as the oil temperature is determined by the thermal oil level sensor installed as standard on every vehicle!

NOTE for E39 and E38 models: Only for vehicles from year 09/1997 and high instrument cluster! (For vehicles prior to 09/1997, the thermal oil level sensor must be replaced so that the eCombi module works)

The installation is very simple: The module is only connected with 6 cables: 5 cables at the plug of the instrument cluster and one cable at the plug of the lamp module.