I wonder which general?
Not surprising though, Mercedes were just as popular back than as they are today. However it being an un armored open top car I would say it would be either a general staff car or used early in the war than put away. After Heydrich was assassinated Hitler ordered that anyone of any importance only travel in armored closed top cars.
Also isn't it neat that MB still provides parts support, GM on the other hand wouldn't want to know anything!