Dead end technology. MB has abandoned development of new diesel engines for cars. There's just no market for them anymore. They're being banned in most European cities and the cost to clean up their emissions just keeps going up. These engines have no future. Mercedes is desperate to catch up with Tesla and a few of the other manufacturers are way ahead of them in EVs.
Aluminum block diesels have been around for decades, it's nothing new. They generally get better fuel economy than iron block with less overheating issues.

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CENSORED due to not family friendly words