I'm not sure how much Diess could bring to the table for Tesla.
He has management experience in one of the few companies larger than Tesla - but how relevant is that? His experience is in a heavily politicised organisation trying to adapt a long history of ICE manufacturing into the new world. Tesla runs under a benevolent dictatorship under Elon.
He is very well connected in German/EU politics which might be useful to open doors or perhaps change Tesla's image in certain parts of Europe ("Tesla now has a proper vehicle manufacturing leadership"). The political element is probably less relevant these days as governments all over the world are throwing offers at Tesla to bring manufacturing to their shores, but could still be useful negotiating with German work councils.
He's probably best used at Tesla as in a fluffy job such as "policy expert" or "thought leader" who can help out with negotiations through the EU bureaucracy.
@avoigt What are your thoughts?
My opinion is that despite I really appreciate Diess in trying to turn the VW tanker around he is not a valuable asset for Tesla and Elon will not hire him. I actually believe that considering Elons temperament he would fire Diess very quickly again.
Tesla is already well connected to major German politicians, Automakers, and Regulators.
Diess is valuable for the other German Automakers but not for Tesla