In the past software updates on car modules came bundled in integration levels to make sure the modules work together. If you had an update, the option list in the car was updated to reflect the integration level. I am not sure if MB is still treating updates like that, but if so then you cannot flash MBUX alone, but need to do it as a bundle to guarantee compatibility with other modules. This could explain why it takes so many hours for them to update the units.
You can flash the MBUX itself, the update files are about 8-10GB via DoIP and because they are heavily compressed it takes ages to do.
I have managed to do it in 2/3 hours with a faster laptop. (I run a mercedes specialist company, which specialises in coding)
Also another misconception is that the instrument cluster is part of the MBUX update, however the instrument cluster is a totally different system (infact the control unit for it sits under the front left seat).
The only grouped updates are the ECU, so if updating ECU, the Transmission control unit & power train control unit need to be updated at the same time. Dealers hate FUP updates as it takes up a bay in their workshop for couple of hours, and the mercedes guidance is that updates should only be done if there is a problem with the mbux system, otherwise generally best to avoid.
If you really want it updating, just say your mbux keeps crashing and screen turns off and theyll update it for you under warranty.
