Sounds like a very reasonable idea, because the gas-stations (right term?) here mostly have electronic tyre filling systems - and these do not work with the hidden valves on my XKR's BBS. And you're right: Going with 250 Km/h on a nearly flat tire could be 'a little bit' ridiculous...

BTW: Did any of the XKR X100-models have manufacturer-equipped TPMS?

So i did a quick research, but couldn't find more detail info for the wiring - so far i've seen, the Koolertron-device is connected between rear-camera and AV-Diplay with an internal av-switch. Not so much of a problem to connect to the nav-screen, but you need an AV-RGB converter, as it is descripted here in several threads (eg from WhiteXKR IIRC). Or do you have some info of a (OEM-)device, that can directly connect to RGBs? Would be a lot cheaper then, i think... or have you seen a device, that can otherwise be connected to a car-pc, maybe via serial or RS485, CAN?

Small update to my work so far (my bad, bad girlfriend urged me on a holiday-trip :-):
I programmed a new firmware for the Arduino's USB-Interface (ATMEL atmega u16), so that i can switch the IF between serial and HID keyboard-function by button. So i can debug my soft via serial and otherwise send 'legacy' keycodes to the WP9900 android-unit, i plan to integrate into the car.

So my software on the arduino should function as followes:
- you push one of the buttons at the OEM-Naviscreen, or maybe on the steering wheel
- the keypress is send via Ai-net-bus to the original Nav-box-connector in the trunk - now taken over by the Arduino-IF
- there the message is decoded (most commands I've 'decyphered' so far)
- my IF sends an appropriate Keycode to the android-box in the trunk via USB
- further on the soft has to emulate the initial handshaking between HU and Nav-box, because as it is the same prob with replacing the CD-changer, the HU must 'think' that the Alpine-navbox is still there.
- VOILA: fully integrated
The only drawback: to fear the worst, i will need a few month to get everything together...

greetings from germany

Wolf