i did not go forward with it, as i could not find the factory mounting points in the wheel wells - i pulled the covers, and for the sake of my life i could not figure where the factory brackets would go... meanwhile the life got in the way, and i left the project behind, even though, it is absolutely doable:

the RDC module goes into the glove compartment area, the bracket to hold it is already there, then you would need the appropriate A169 module, the one that has the Hill Descent, the seat heaters, and the RDC button - that one is fully occupied, the RDC button is the last one on the right (the last one is the right seat heater, but there is a single slot space between the RDC and the seat heater).

I have connected the A85 module and the A169 module, wired them up and the iBus has recognised the presence of the new module... I just did not run the antennae wires...

The principal difference between the TPMS and the RDC is tha fact that he RDC is measuring the absolute value of the internalpressure and reports it through the system, while the TPMS is measuring the rotational speed of individual wheels and compares them to the other ones - and reports the 10% in the difference... As a result, the RDC will report gradual loss of pressure in all 4 tires as a reference point is a fixed value (during the reset process), and the TPMS will not report the even loss of pressure in all 4 tires as the reference point is within thse 4 tires... Other than that - the RDC is more complex as it adds more hardware, and the TPMS is simpler, as it is using the TPMS module in addition to ABS system

36-14-6-751-371 the RDC module A85 - 1
36-11-8-378-753 the receiving antennas - 4
36-11-6-751-503 the front antenna holders - 2
36-11-6-751-504 the rear antenna holders - 2
36-23-6-779-490 the tire monitors with valves - 4
61-31-8-373-740 the module A169 with RDC button - 1
61-13-8-373-650 32-pin connector for the RDC module
61-13-8-373-648 cover cap for the connector for RDC module
61-13-8-365-340 2-pin connector for antennas - 4
61-13-0-006-665 bushing contact, same as Digi-key A28327-ND
61-13-8-366-245 rubber grommets
61-13-1-387-144 ground connector
61-12-1-387-146 ground connector

here is the pinout for module A85

1 pin 12 on X332 for A1 - general module glove compartment
2
3 pin 18 on A169 - the button central console
4
5 pin 1 on B43 - fr/left antenna front left
6 shielding front left
7 pin 1 on B47 - fr/right antenna front right
8 pin 1 on B45 - rear/left antenna rear left
9 shielding rear left
10 pin 1 on B44 - rear/right antenna rear right
11
12
13
14 pin 4 on A169 - the button central console
15 pin 24 on X10460 glove compartment
16 to ground on X596 glove compartment
17 pin 4 on X253 for A1 - general module glove compartment
18
19
20
21 pin 2 on B43 - fr/left antenna front left
22 shielding front right
23 pin 2 on B47 - fr/right antenna front right
24 pin 2 on B45 - rear left antenna rear left
25 shieldingrear right
26 pin 2 on B44 - rear/right antenna rear right
27
28
29
30
31 pin 15 on X10461 glove compartment
32