The e53 uses ibus for the entertainment system. This is basically a dedicated comm bus that is hardware/electrically the same as the kbus. I see that parrot has an interface for the kbus but says its compatible >2007. You can probably make it work but not a lot of guys here have hacked their ibus. I've done a lot of research as I'm planning (after all the other projects) to do a CarPC.
I'd Google for MKi9100 ibus integration. I see more stuff on the German pages, but you need to run them through a translator, unless you speak German.

You may also want to be more specific on what you are installing it in. It would help if you added your vehicles to your signature.

Good luck

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