Diess posted a selfie with Musk after the event. Musk praised the ID3, and Diess beamed.
The mutual esteem has apparently existed for some time. In 2015, Musk tried to poach Diess, who was then BMW's head of development, to become CEO of Tesla.
Diess declined Musk's offer and instead joined VW as a management board member. Diess became VW's CEO in 2018.
Musk's offer was first reported by Business Insider last week. Sources with knowledge of the matter confirmed the report to Automobilwoche, a sibling publication of Automotive News, and to the German business daily Handelsblatt.
Tesla had drawn up a contract for Diess that was ready to be signed, the sources said. Musk wanted to hand over the CEO post to Diess so that he could concentrate on his role as Tesla chairman. At the time, the Tesla founder was still performing both functions.